Systems and methods for using a client agent to manage http authentication cookies

ABSTRACT

Systems and methods are described for using a client agent to manage HTTP authentication cookies. One method includes intercepting, by a client agent executing on a client, a connection request from the client; establishing, by the client agent, a transport layer virtual private network connection with a network appliance; transmitting, by the client agent via the established connection, an HTTP request comprising an authentication cookie; and transmitting, by the client agent via the connection, the connection request. A second method includes intercepting, by a client agent executing on a client, an HTTP communication comprising a cookie from an appliance on a virtual private network to the client; removing, by the client agent, the cookie from the HTTP communication; storing, by the client agent, the received cookie; transmitting, by the client agent, the modified HTTP communication to an application executing on the client; intercepting, by the client agent, an HTTP request from the client; inserting, by the client agent in the HTTP request, the received cookie; and transmitting the modified HTTP request to the appliance. Corresponding systems are also described.

FIELD OF THE INVENTION

The present invention relates to networking technologies, andspecifically the use of a client agent to intercept HTTP requests andresponses and manage cookies in order to provide optimizedcommunications.

BACKGROUND OF THE INVENTION

Many applications, such as web browsers, communicate with servers usingHTTP. This may result in a significant amount of traffic over a givennetwork being HTTP traffic. Thus, many benefits may be obtained byoptimizing and controlling the flow of HTTP traffic in a virtual privatenetwork. For example, caching may be used to improve service forrepeated HTTP requests. Or, for example, benefits may be obtained bycontrolling the names of resources requested, and any data sent alongwith a request. However, the number of different applications using HTTPmay make impractical the task of adapting all HTTP applicationsspecifically for operating in a virtual private network environment.

Many virtual private networks and resources within them also requireuser authentication. For example, a user of a virtual private networkmay be asked to provide a name and password in order to log on to thenetwork, and also to gain access to certain resources. HTTP cookies maybe used to pass authentication information from a client to a virtualprivate network appliance. Often web browsers are used to manage theseauthentication cookies.

Several problems may arise in the use of web browsers to manage HTTPcookies to authenticate users of a virtual private network. For example,a user may use a web browser to open a plurality of simultaneousconnections to a virtual private network. It may be desirable in thiscase that the authentication cookie from the first connection be usedagain to establish the second connection so the user does not have toreenter the authentication information. This feature may be difficult toimplement given the variety of cookie management policies acrossdifferent browsers, such as expiration time, and accessibility of thecookie cache. Also, for example, a user may attempt to open a non-HTTPconnection via the virtual private network, in which case the webbrowser may not be used, meaning the authentication cookie may not beaccessible.

Thus there exists a need for a client agent which can intercept andparse HTTP communications and manage cookies in a virtual privatenetwork environment.

BRIEF SUMMARY OF THE INVENTION

The present invention relates to systems and methods for using anHTTP-aware client agent. In one aspect, the present invention is amethod for using a client agent operating in a virtual private networkenvironment to intercept HTTP communications. In one embodiment, themethod comprises: intercepting at the network layer, by a client agentexecuting on a client, an HTTP request from an application executing onthe client; modifying the HTTP request; and transmitting, via atransport layer connection, the modified HTTP request to a server. Insome embodiments, the method may comprise adding, removing, or modifyingat least one cookie in the HTTP request. In other embodiments, themethod may comprise modifying at least one name-value pair contained inthe HTTP request.

In a second aspect, the present invention relates to a computerimplemented system for using a client agent operating in a virtualprivate network environment to intercept HTTP communications. In oneembodiment, the system comprises: a client computing device; and aclient agent which executes on the client; intercepts at the networklayer an HTTP request from an application executing on the client;modifies the HTTP request; and transmits, via a transport layerconnection, the modified HTTP request to a server.

In third aspect, the present invention is a method for using a clientagent to enable HTTP cookie authentication in non-HTTP communicationsfrom a client, the method comprising: intercepting, by a client agentexecuting on a client, a connection request from the client;establishing, by the client agent, a transport layer virtual privatenetwork connection with a network appliance; transmitting, by the clientagent via the established connection, an HTTP request comprising anauthentication cookie; and transmitting, by the client agent via theconnection, the connection request.

In a fourth aspect the present invention is a computer implementedsystem for using a client agent to enable HTTP cookie authentication innon-HTTP communications from a client, the system comprising: a clientcomputing device; and a client agent executing on the client, whichintercepts a connection request from the client; establishes a transportlayer virtual private network connection with a network appliance;transmits, by the client agent via the established connection, an HTTPrequest comprising an authentication cookie; and transmits, by theclient agent via the connection, the connection request.

In a fifth aspect, the present invention is a method for using a clientagent to enable secure authentication in a virtual private networkenvironment using an HTTP cookie, the method comprising: intercepting,by a client agent executing on a client, an HTTP communicationcomprising a cookie from an appliance on a virtual private network tothe client; removing, by the client agent, the cookie from the HTTPcommunication; storing, by the client agent, the received cookie;transmitting, by the client agent, the modified HTTP communication to anapplication executing on the client; intercepting, by the client agent,an HTTP request from the client; inserting, by the client agent in theHTTP request, the received cookie; and transmitting the modified HTTPrequest to the appliance.

In a sixth aspect, the present invention is a computer implementedsystem for using a client agent to enable secure authentication in avirtual private network environment using an HTTP cookie, the systemcomprising: a client computing device; and a client agent executing onthe client which intercepts an HTTP communication comprising a cookiefrom an appliance on a virtual private network to the client; removesthe cookie from the HTTP communication; stores the received cookie;transmits the modified HTTP communication to an application executing onthe client; intercepts, by the client agent, an HTTP request from theclient; inserting, by the client agent in the HTTP request, the receivedcookie; and transmitting the modified HTTP request to the appliance.

The details of various embodiments of the invention are set forth in theaccompanying drawings and the description below.

BRIEF DESCRIPTION OF THE FIGURES

The foregoing and other objects, aspects, features, and advantages ofthe invention will become more apparent and better understood byreferring to the following description taken in conjunction with theaccompanying drawings, in which:

FIG. 1A is a block diagram of an embodiment of a network environment fora client to access a server via an appliance;

FIG. 1B is a block diagram of an embodiment of an environment fordelivering a computing environment from a server to a client via anappliance;

FIGS. 1C and 1D are block diagrams of embodiments of a computing device;

FIG. 2A is a block diagram of an embodiment of an appliance forprocessing communications between a client and a server;

FIG. 2B is a block diagram of another embodiment of an appliance foroptimizing, accelerating, load-balancing and routing communicationsbetween a client and a server;

FIG. 3 is a block diagram of an embodiment of a client for communicatingwith a server via the appliance;

FIG. 4 is a block diagram of one embodiment of a method for using aclient agent operating in a virtual private network environment tointercept HTTP communications;

FIG. 5 is a block diagram of one embodiment of a method for using aclient agent to enable HTTP cookie authentication.

FIG. 6 is a block diagram of a method for using a client agent to enablesecure authentication in a virtual private network environment using anHTTP cookie

FIG. 7 is a flow diagram depicting one embodiment of a method forcreating an efficient update to a previously stored file;

FIG. 8 is a flow diagram depicting another embodiment of a method forcreating efficient updates to a previously stored file;

FIG. 9 is a flow diagram depicting another embodiment of methods forcreating and receiving efficient updates to a previously stored file;

FIG. 10 is a flow diagram depicting one embodiment of a method forassembling a second file from a previously stored first file and a thirdfile comprising sequences of data from the second file andrepresentations of locations and lengths of sequences of data present inboth the first and second files; and

FIG. 11 is a flow diagram depicting one embodiment of a method fordetermining a file transmission method.

The features and advantages of the present invention will become moreapparent from the detailed description set forth below when taken inconjunction with the drawings, in which like reference charactersidentify corresponding elements throughout. In the drawings, likereference numbers generally indicate identical, functionally similar,and/or structurally similar elements.

DETAILED DESCRIPTION OF THE INVENTION A. Network and ComputingEnvironment

Prior to discussing the specifics of embodiments of the systems andmethods of an appliance and/or client, it may be helpful to discuss thenetwork and computing environments in which such embodiments may bedeployed. Referring now to FIG. 1A, an embodiment of a networkenvironment is depicted. In brief overview, the network environmentcomprises one or more clients 102 a-102 n (also generally referred to aslocal machine(s) 102, or client(s) 102) in communication with one ormore servers 106 a-106 n (also generally referred to as server(s) 106,or remote machine(s) 106) via one or more networks 104, 104′ (generallyreferred to as network 104). In some embodiments, a client 102communicates with a server 106 via an appliance 200.

Although FIG. 1A shows a network 104 and a network 104′ between theclients 102 and the servers 106, the clients 102 and the servers 106 maybe on the same network 104. The networks 104 and 104′ can be the sametype of network or different types of networks. The network 104 and/orthe network 104′ can be a local-area network (LAN), such as a companyIntranet, a metropolitan area network (MAN), or a wide area network(WAN), such as the Internet or the World Wide Web. In one embodiment,network 104′ may be a private network and network 104 may be a publicnetwork. In some embodiments, network 104 may be a private network andnetwork 104′ a public network. In another embodiment, networks 104 and104′ may both be private networks. In some embodiments, clients 102 maybe located at a branch office of a corporate enterprise communicatingvia a WAN connection over the network 104 to the servers 106 located ata corporate data center.

The network 104 and/or 104′ be any type and/or form of network and mayinclude any of the following: a point to point network, a broadcastnetwork, a wide area network, a local area network, a telecommunicationsnetwork, a data communication network, a computer network, an ATM(Asynchronous Transfer Mode) network, a SONET (Synchronous OpticalNetwork) network, a SDH (Synchronous Digital Hierarchy) network, awireless network and a wireline network. In some embodiments, thenetwork 104 may comprise a wireless link, such as an infrared channel orsatellite band. The topology of the network 104 and/or 104′ may be abus, star, or ring network topology. The network 104 and/or 104′ andnetwork topology may be of any such network or network topology as knownto those ordinarily skilled in the art capable of supporting theoperations described herein.

As shown in FIG. 1A, the appliance 200, which also may be referred to asan interface unit 200 or gateway 200, is shown between the networks 104and 104′. In some embodiments, the appliance 200 may be located onnetwork 104. For example, a branch office of a corporate enterprise maydeploy an appliance 200 at the branch office. In other embodiments, theappliance 200 may be located on network 104′. For example, an appliance200 may be located at a corporate data center. In yet anotherembodiment, a plurality of appliances 200 may be deployed on network104. In some embodiments, a plurality of appliances 200 may be deployedon network 104′. In one embodiment, a first appliance 200 communicateswith a second appliance 200′. In other embodiments, the appliance 200could be a part of any client 102 or server 106 on the same or differentnetwork 104,104′ as the client 102. One or more appliances 200 may belocated at any point in the network or network communications pathbetween a client 102 and a server 106.

In one embodiment, the system may include multiple, logically-groupedservers 106. In these embodiments, the logical group of servers may bereferred to as a server farm 38. In some of these embodiments, theserves 106 may be geographically dispersed. In some cases, a farm 38 maybe administered as a single entity. In other embodiments, the serverfarm 38 comprises a plurality of server farms 38. In one embodiment, theserver farm executes one or more applications on behalf of one or moreclients 102.

The servers 106 within each farm 38 can be heterogeneous. One or more ofthe servers 106 can operate according to one type of operating systemplatform (e.g., WINDOWS NT, manufactured by Microsoft Corp. of Redmond,Wash.), while one or more of the other servers 106 can operate onaccording to another type of operating system platform (e.g., Unix orLinux). The servers 106 of each farm 38 do not need to be physicallyproximate to another server 106 in the same farm 38. Thus, the group ofservers 106 logically grouped as a farm 38 may be interconnected using awide-area network (WAN) connection or medium-area network (MAN)connection. For example, a farm 38 may include servers 106 physicallylocated in different continents or different regions of a continent,country, state, city, campus, or room. Data transmission speeds betweenservers 106 in the farm 38 can be increased if the servers 106 areconnected using a local-area network (LAN) connection or some form ofdirect connection.

Servers 106 may be referred to as a file server, application server, webserver, proxy server, or gateway server. In some embodiments, a server106 may have the capacity to function as either an application server oras a master application server. In one embodiment, a server 106 mayinclude an Active Directory. The clients 102 may also be referred to asclient nodes or endpoints. In some embodiments, a client 102 has thecapacity to function as both a client node seeking access toapplications on a server and as an application server providing accessto hosted applications for other clients 102 a-102 n.

In some embodiments, a client 102 communicates with a server 106. In oneembodiment, the client 102 communicates directly with one of the servers106 in a farm 38. In another embodiment, the client 102 executes aprogram neighborhood application to communicate with a server 106 in afarm 38. In still another embodiment, the server 106 provides thefunctionality of a master node. In some embodiments, the client 102communicates with the server 106 in the farm 38 through a network 104.Over the network 104, the client 102 can, for example, request executionof various applications hosted by the servers 106 a-106 n in the farm 38and receive output of the results of the application execution fordisplay. In some embodiments, only the master node provides thefunctionality required to identify and provide address informationassociated with a server 106′ hosting a requested application.

In one embodiment, the server 106 provides functionality of a webserver. In another embodiment, the server 106 a receives requests fromthe client 102, forwards the requests to a second server 106 b andresponds to the request by the client 102 with a response to the requestfrom the server 106 b. In still another embodiment, the server 106acquires an enumeration of applications available to the client 102 andaddress information associated with a server 106 hosting an applicationidentified by the enumeration of applications. In yet anotherembodiment, the server 106 presents the response to the request to theclient 102 using a web interface. In one embodiment, the client 102communicates directly with the server 106 to access the identifiedapplication. In another embodiment, the client 102 receives applicationoutput data, such as display data, generated by an execution of theidentified application on the server 106.

Referring now to FIG. 1B, a network environment for delivering and/oroperating a computing environment on a client 102 is depicted. In someembodiments, a server 106 includes an application delivery system 190for delivering a computing environment or an application and/or datafile to one or more clients 102. In brief overview, a client 10 is incommunication with a server 106 via network 104, 104′ and appliance 200.For example, the client 102 may reside in a remote office of a company,e.g., a branch office, and the server 106 may reside at a corporate datacenter. The client 102 comprises a client agent 120, and a computingenvironment 15. The computing environment 15 may execute or operate anapplication that accesses, processes or uses a data file. The computingenvironment 15, application and/or data file may be delivered via theappliance 200 and/or the server 106.

In some embodiments, the appliance 200 accelerates delivery of acomputing environment 15, or any portion thereof, to a client 102. Inone embodiment, the appliance 200 accelerates the delivery of thecomputing environment 15 by the application delivery system 190. Forexample, the embodiments described herein may be used to acceleratedelivery of a streaming application and data file processable by theapplication from a central corporate data center to a remote userlocation, such as a branch office of the company. In another embodiment,the appliance 200 accelerates transport layer traffic between a client102 and a server 106. The appliance 200 may provide accelerationtechniques for accelerating any transport layer payload from a server106 to a client 102, such as: 1) transport layer connection pooling, 2)transport layer connection multiplexing, 3) transport control protocolbuffering, 4) compression and 5) caching. In some embodiments, theappliance 200 provides load balancing of servers 106 in responding torequests from clients 102. In other embodiments, the appliance 200 actsas a proxy or access server to provide access to the one or more servers106. In another embodiment, the appliance 200 provides a secure virtualprivate network connection from a first network 104 of the client 102 tothe second network 104′ of the server 106, such as an SSL VPNconnection. It yet other embodiments, the appliance 200 providesapplication firewall security, control and management of the connectionand communications between a client 102 and a server 106.

In some embodiments, the application delivery management system 190provides application delivery techniques to deliver a computingenvironment to a desktop of a user, remote or otherwise, based on aplurality of execution methods and based on any authentication andauthorization policies applied via a policy engine 195. With thesetechniques, a remote user may obtain a computing environment and accessto server stored applications and data files from any network connecteddevice 100. In one embodiment, the application delivery system 190 mayreside or execute on a server 106. In another embodiment, theapplication delivery system 190 may reside or execute on a plurality ofservers 106 a-106 n. In some embodiments, the application deliverysystem 190 may execute in a server farm 38. In one embodiment, theserver 106 executing the application delivery system 190 may also storeor provide the application and data file. In another embodiment, a firstset of one or more servers 106 may execute the application deliverysystem 190, and a different server 106 n may store or provide theapplication and data file. In some embodiments, each of the applicationdelivery system 190, the application, and data file may reside or belocated on different servers. In yet another embodiment, any portion ofthe application delivery system 190 may reside, execute or be stored onor distributed to the appliance 200, or a plurality of appliances.

The client 102 may include a computing environment 15 for executing anapplication that uses or processes a data file. The client 102 vianetworks 104, 104′ and appliance 200 may request an application and datafile from the server 106. In one embodiment, the appliance 200 mayforward a request from the client 102 to the server 106. For example,the client 102 may not have the application and data file stored oraccessible locally. In response to the request, the application deliverysystem 190 and/or server 106 may deliver the application and data fileto the client 102. For example, in one embodiment, the server 106 maytransmit the application as an application stream to operate incomputing environment 15 on client 102.

In some embodiments, the application delivery system 190 comprises anyportion of the Citrix Access Suite™ by Citrix Systems, Inc., such as theMetaFrame or Citrix Presentation Server™ and/or any of the Microsoft®Windows Terminal Services manufactured by the Microsoft Corporation. Inone embodiment, the application delivery system 190 may deliver one ormore applications to clients 102 or users via a remote-display protocolor otherwise via remote-based or server-based computing. In anotherembodiment, the application delivery system 190 may deliver one or moreapplications to clients or users via steaming of the application.

In one embodiment, the application delivery system 190 includes a policyengine 195 for controlling and managing the access to, selection ofapplication execution methods and the delivery of applications. In someembodiments, the policy engine 195 determines the one or moreapplications a user or client 102 may access. In another embodiment, thepolicy engine 195 determines how the application should be delivered tothe user or client 102, e.g., the method of execution. In someembodiments, the application delivery system 190 provides a plurality ofdelivery techniques from which to select a method of applicationexecution, such as a server-based computing, streaming or delivering theapplication locally to the client 120 for local execution.

In one embodiment, a client 102 requests execution of an applicationprogram and the application delivery system 190 comprising a server 106selects a method of executing the application program. In someembodiments, the server 106 receives credentials from the client 102. Inanother embodiment, the server 106 receives a request for an enumerationof available applications from the client 102. In one embodiment, inresponse to the request or receipt of credentials, the applicationdelivery system 190 enumerates a plurality of application programsavailable to the client 102. The application delivery system 190receives a request to execute an enumerated application. The applicationdelivery system 190 selects one of a predetermined number of methods forexecuting the enumerated application, for example, responsive to apolicy of a policy engine. The application delivery system 190 mayselect a method of execution of the application enabling the client 102to receive application-output data generated by execution of theapplication program on a server 106. The application delivery system 190may select a method of execution of the application enabling the localmachine 10 to execute the application program locally after retrieving aplurality of application files comprising the application. In yetanother embodiment, the application delivery system 190 may select amethod of execution of the application to stream the application via thenetwork 104 to the client 102.

A client 102 may execute, operate or otherwise provide an application,which can be any type and/or form of software, program, or executableinstructions such as any type and/or form of web browser, web-basedclient, client-server application, a thin-client computing client, anActiveX control, or a Java applet, or any other type and/or form ofexecutable instructions capable of executing on client 102. In someembodiments, the application may be a server-based or a remote-basedapplication executed on behalf of the client 102 on a server 106. In oneembodiments the server 106 may display output to the client 102 usingany thin-client or remote-display protocol, such as the IndependentComputing Architecture (ICA) protocol manufactured by Citrix Systems,Inc. of Ft. Lauderdale, Fla. or the Remote Desktop Protocol (RDP)manufactured by the Microsoft Corporation of Redmond, Wash. Theapplication can use any type of protocol and it can be, for example, anHTTP client, an FTP client, an Oscar client, or a Telnet client. Inother embodiments, the application comprises any type of softwarerelated to VoIP communications, such as a soft IP telephone. In furtherembodiments, the application comprises any application related toreal-time data communications, such as applications for streaming videoand/or audio.

In some embodiments, the server 106 or a server farm 38 may be runningone or more applications, such as an application providing a thin-clientcomputing or remote display presentation application. In one embodiment,the server 106 or server farm 38 executes as an application, any portionof the Citrix Access Suite™ by Citrix Systems, Inc., such as theMetaFrame or Citrix Presentation Server™, and/or any of the Microsoft®Windows Terminal Services manufactured by the Microsoft Corporation. Inone embodiment, the application is an ICA client, developed by CitrixSystems, Inc. of Fort Lauderdale, Fla. In other embodiments, theapplication includes a Remote Desktop (RDP) client, developed byMicrosoft Corporation of Redmond, Wash. Also, the server 106 may run anapplication, which for example, may be an application server providingemail services such as Microsoft Exchange manufactured by the MicrosoftCorporation of Redmond, Wash., a web or Internet server, or a desktopsharing server, or a collaboration server. In some embodiments, any ofthe applications may comprise any type of hosted service or products,such as GoToMeeting™ provided by Citrix Online Division, Inc. of SantaBarbara, Calif., WebEx™ provided by WebEx, Inc. of Santa Clara, Calif.,or Microsoft Office Live Meeting provided by Microsoft Corporation ofRedmond, Wash.

The client 102, server 106, and appliance 200 may be deployed as and/orexecuted on any type and form of computing device, such as a computer,network device or appliance capable of communicating on any type andform of network and performing the operations described herein. FIGS. 1Cand 1D depict block diagrams of a computing device 100 useful forpracticing an embodiment of the client 102, server 106 or appliance 200.As shown in FIGS. 1C and 1D, each computing device 100 includes acentral processing unit 101, and a main memory unit 122. As shown inFIG. 1C, a computing device 100 may include a visual display device 124,a keyboard 126 and/or a pointing device 127, such as a mouse. Eachcomputing device 100 may also include additional optional elements, suchas one or more input/output devices 130 a-130 b (generally referred tousing reference numeral 130), and a cache memory 140 in communicationwith the central processing unit 101.

The central processing unit 101 is any logic circuitry that responds toand processes instructions fetched from the main memory unit 122. Inmany embodiments, the central processing unit is provided by amicroprocessor unit, such as: those manufactured by Intel Corporation ofMountain View, Calif.; those manufactured by Motorola Corporation ofSchaumburg, Ill.; those manufactured by Transmeta Corporation of SantaClara, Calif.; the RS/6000 processor, those manufactured byInternational Business Machines of White Plains, N.Y.; or thosemanufactured by Advanced Micro Devices of Sunnyvale, Calif. Thecomputing device 100 may be based on any of these processors, or anyother processor capable of operating as described herein.

Main memory unit 122 may be one or more memory chips capable of storingdata and allowing any storage location to be directly accessed by themicroprocessor 101, such as Static random access memory (SRAM), BurstSRAM or SynchBurst SRAM (BSRAM), Dynamic random access memory (DRAM),Fast Page Mode DRAM (FPM DRAM), Enhanced DRAM (EDRAM), Extended DataOutput RAM (EDO RAM), Extended Data Output DRAM (EDO DRAM), BurstExtended Data Output DRAM (BEDO DRAM), Enhanced DRAM (EDRAM),synchronous DRAM (SDRAM), JEDEC SRAM, PC100 SDRAM, Double Data RateSDRAM (DDR SDRAM), Enhanced SDRAM (ESDRAM), SyncLink DRAM (SLDRAM),Direct Rambus DRAM (DRDRAM), or Ferroelectric RAM (FRAM). The mainmemory 122 may be based on any of the above described memory chips, orany other available memory chips capable of operating as describedherein. In the embodiment shown in FIG. 1C, the processor 101communicates with main memory 122 via a system bus 150 (described inmore detail below). FIG. 1C depicts an embodiment of a computing device100 in which the processor communicates directly with main memory 122via a memory port 103. For example, in FIG. 1D the main memory 122 maybe DRDRAM.

FIG. 1D depicts an embodiment in which the main processor 101communicates directly with cache memory 140 via a secondary bus,sometimes referred to as a backside bus. In other embodiments, the mainprocessor 101 communicates with cache memory 140 using the system bus150. Cache memory 140 typically has a faster response time than mainmemory 122 and is typically provided by SRAM, BSRAM, or EDRAM. In theembodiment shown in FIG. 1C, the processor 101 communicates with variousI/O devices 130 via a local system bus 150. Various busses may be usedto connect the central processing unit 101 to any of the I/O devices130, including a VESA VL bus, an ISA bus, an EISA bus, a MicroChannelArchitecture (MCA) bus, a PCI bus, a PCI-X bus, a PCI-Express bus, or aNuBus. For embodiments in which the I/O device is a video display 124,the processor 101 may use an Advanced Graphics Port (AGP) to communicatewith the display 124. FIG. 1D depicts an embodiment of a computer 100 inwhich the main processor 101 communicates directly with I/O device 130via HyperTransport, Rapid I/O, or InfiniBand. FIG. 1D also depicts anembodiment in which local busses and direct communication are mixed: theprocessor 101 communicates with I/O device 130 using a localinterconnect bus while communicating with I/O device 130 directly.

The computing device 100 may support any suitable installation device116, such as a floppy disk drive for receiving floppy disks such as3.5-inch, 5.25-inch disks or ZIP disks, a CD-ROM drive, a CD-R/RW drive,a DVD-ROM drive, tape drives of various formats, USB device, hard-driveor any other device suitable for installing software and programs suchas any client agent 120, or portion thereof. The computing device 100may further comprise a storage device 128, such as one or more hard diskdrives or redundant arrays of independent disks, for storing anoperating system and other related software, and for storing applicationsoftware programs such as any program related to the client agent 120.Optionally, any of the installation devices 116 could also be used asthe storage device 128. Additionally, the operating system and thesoftware can be run from a bootable medium, for example, a bootable CD,such as KNOPPIX®, a bootable CD for GNU/Linux that is available as aGNU/Linux distribution from knoppix.net.

Furthermore, the computing device 100 may include a network interface118 to interface to a Local Area Network (LAN), Wide Area Network (WAN)or the Internet through a variety of connections including, but notlimited to, standard telephone lines, LAN or WAN links (e.g., 802.11,T1, T3, 56 kb, X.25), broadband connections (e.g., ISDN, Frame Relay,ATM), wireless connections, or some combination of any or all of theabove. The network interface 118 may comprise a built-in networkadapter, network interface card, PCMCIA network card, card bus networkadapter, wireless network adapter, USB network adapter, modem or anyother device suitable for interfacing the computing device 100 to anytype of network capable of communication and performing the operationsdescribed herein.

A wide variety of I/O devices 130 a-130 n may be present in thecomputing device 100. Input devices include keyboards, mice, trackpads,trackballs, microphones, and drawing tablets. Output devices includevideo displays, speakers, inkjet printers, laser printers, anddye-sublimation printers. The I/O devices 130 may be controlled by anI/O controller 123 as shown in FIG. 1C. The I/O controller may controlone or more I/O devices such as a keyboard 126 and a pointing device127, e.g., a mouse or optical pen. Furthermore, an I/O device may alsoprovide storage 128 and/or an installation medium 116 for the computingdevice 100. In still other embodiments, the computing device 100 mayprovide USB connections to receive handheld USB storage devices such asthe USB Flash Drive line of devices manufactured by Twintech Industry,Inc. of Los Alamitos, Calif.

In some embodiments, the computing device 100 may comprise or beconnected to multiple display devices 124 a-124 n, which each may be ofthe same or different type and/or form. As such, any of the I/O devices130 a-130 n and/or the I/O controller 123 may comprise any type and/orform of suitable hardware, software, or combination of hardware andsoftware to support, enable or provide for the connection and use ofmultiple display devices 124 a-124 n by the computing device 100. Forexample, the computing device 100 may include any type and/or form ofvideo adapter, video card, driver, and/or library to interface,communicate, connect or otherwise use the display devices 124 a-124 n.In one embodiment, a video adapter may comprise multiple connectors tointerface to multiple display devices 124 a-124 n. In other embodiments,the computing device 100 may include multiple video adapters, with eachvideo adapter connected to one or more of the display devices 124 a-124n. In some embodiments, any portion of the operating system of thecomputing device 100 may be configured for using multiple displays 124a-124 n. In other embodiments, one or more of the display devices 124a-124 n may be provided by one or more other computing devices, such ascomputing devices 100 a and 100 b connected to the computing device 100,for example, via a network. These embodiments may include any type ofsoftware designed and constructed to use another computer's displaydevice as a second display device 124 a for the computing device 100.One ordinarily skilled in the art will recognize and appreciate thevarious ways and embodiments that a computing device 100 may beconfigured to have multiple display devices 124 a-124 n.

In further embodiments, an I/O device 130 may be a bridge 170 betweenthe system bus 150 and an external communication bus, such as a USB bus,an Apple Desktop Bus, an RS-232 serial connection, a SCSI bus, aFireWire bus, a FireWire 800 bus, an Ethernet bus, an AppleTalk bus, aGigabit Ethernet bus, an Asynchronous Transfer Mode bus, a HIPPI bus, aSuper HIPPI bus, a SerialPlus bus, a SCI/LAMP bus, a FibreChannel bus,or a Serial Attached small computer system interface bus.

A computing device 100 of the sort depicted in FIGS. 1C and 1D typicallyoperate under the control of operating systems, which control schedulingof tasks and access to system resources. The computing device 100 can berunning any operating system such as any of the versions of theMicrosoft® Windows operating systems, the different releases of the Unixand Linux operating systems, any version of the Mac OS® for Macintoshcomputers, any embedded operating system, any real-time operatingsystem, any open source operating system, any proprietary operatingsystem, any operating systems for mobile computing devices, or any otheroperating system capable of running on the computing device andperforming the operations described herein. Typical operating systemsinclude: WINDOWS 3.x, WINDOWS 95, WINDOWS 98, WINDOWS 2000, WINDOWS NT3.51, WINDOWS NT 4.0, WINDOWS CE, and WINDOWS XP, all of which aremanufactured by Microsoft Corporation of Redmond, Wash.; MacOS,manufactured by Apple Computer of Cupertino, California; OS/2,manufactured by International Business Machines of Armonk, N.Y.; andLinux, a freely-available operating system distributed by Caldera Corp.of Salt Lake City, Utah, or any type and/or form of a Unix operatingsystem, among others.

In other embodiments, the computing device 100 may have differentprocessors, operating systems, and input devices consistent with thedevice. For example, in one embodiment the computer 100 is a Treo 180,270, 1060, 600 or 650 smart phone manufactured by Palm, Inc. In thisembodiment, the Treo smart phone is operated under the control of thePalmOS operating system and includes a stylus input device as well as afive-way navigator device. Moreover, the computing device 100 can be anyworkstation, desktop computer, laptop or notebook computer, server,handheld computer, mobile telephone, any other computer, or other formof computing or telecommunications device that is capable ofcommunication and that has sufficient processor power and memorycapacity to perform the operations described herein.

B. Appliance Architecture

FIG. 2A illustrates an example embodiment of the appliance 200. Thearchitecture of the appliance 200 in FIG. 2A is provided by way ofillustration only and is not intended to be limiting. As shown in FIG.2, appliance 200 comprises a hardware layer 206 and a software layerdivided into a user space 202 and a kernel space 204.

Hardware layer 206 provides the hardware elements upon which programsand services within kernel space 204 and user space 202 are executed.Hardware layer 206 also provides the structures and elements which allowprograms and services within kernel space 204 and user space 202 tocommunicate data both internally and externally with respect toappliance 200. As shown in FIG. 2, the hardware layer 206 includes aprocessing unit 262 for executing software programs and services, amemory 264 for storing software and data, network ports 266 fortransmitting and receiving data over a network, and an encryptionprocessor 260 for performing functions related to Secure Sockets Layerprocessing of data transmitted and received over the network. In someembodiments, the central processing unit 262 may perform the functionsof the encryption processor 260 in a single processor. Additionally, thehardware layer 206 may comprise multiple processors for each of theprocessing unit 262 and the encryption processor 260. The processor 262may include any of the processors 101 described above in connection withFIGS. 1C and 1D. In some embodiments, the central processing unit 262may perform the functions of the encryption processor 260 in a singleprocessor. Additionally, the hardware layer 206 may comprise multipleprocessors for each of the processing unit 262 and the encryptionprocessor 260. For example, in one embodiment, the appliance 200comprises a first processor 262 and a second processor 262′. In otherembodiments, the processor 262 or 262′ comprises a multi-core processor.

Although the hardware layer 206 of appliance 200 is generallyillustrated with an encryption processor 260, processor 260 may be aprocessor for performing functions related to any encryption protocol,such as the Secure Socket Layer (SSL) or Transport Layer Security (TLS)protocol. In some embodiments, the processor 260 may be a generalpurpose processor (GPP), and in further embodiments, may be haveexecutable instructions for performing processing of any securityrelated protocol.

Although the hardware layer 206 of appliance 200 is illustrated withcertain elements in FIG. 2, the hardware portions or components ofappliance 200 may comprise any type and form of elements, hardware orsoftware, of a computing device, such as the computing device 100illustrated and discussed herein in conjunction with FIGS. 1C and 1D. Insome embodiments, the appliance 200 may comprise a server, gateway,router, switch, bridge or other type of computing or network device, andhave any hardware and/or software elements associated therewith.

The operating system of appliance 200 allocates, manages, or otherwisesegregates the available system memory into kernel space 204 and userspace 204. In example software architecture 200, the operating systemmay be any type and/or form of Unix operating system although theinvention is not so limited. As such, the appliance 200 can be runningany operating system such as any of the versions of the Microsoft®Windows operating systems, the different releases of the Unix and Linuxoperating systems, any version of the Mac OS® for Macintosh computers,any embedded operating system, any network operating system, anyreal-time operating system, any open source operating system, anyproprietary operating system, any operating systems for mobile computingdevices or network devices, or any other operating system capable ofrunning on the appliance 200 and performing the operations describedherein.

The kernel space 204 is reserved for running the kernel 230, includingany device drivers, kernel extensions or other kernel related software.As known to those skilled in the art, the kernel 230 is the core of theoperating system, and provides access, control, and management ofresources and hardware-related elements of the application 104. Inaccordance with an embodiment of the appliance 200, the kernel space 204also includes a number of network services or processes working inconjunction with a cache manager 232. sometimes also referred to as theintegrated cache, the benefits of which are described in detail furtherherein. Additionally, the embodiment of the kernel 230 will depend onthe embodiment of the operating system installed, configured, orotherwise used by the device 200.

In one embodiment, the device 200 comprises one network stack 267, suchas a TCP/IP based stack, for communicating with the client 102 and/orthe server 106. In one embodiment, the network stack 267 is used tocommunicate with a first network, such as network 108, and a secondnetwork 110. In some embodiments, the device 200 terminates a firsttransport layer connection, such as a TCP connection of a client 102,and establishes a second transport layer connection to a server 106 foruse by the client 102, e.g., the second transport layer connection isterminated at the appliance 200 and the server 106. The first and secondtransport layer connections may be established via a single networkstack 267. In other embodiments, the device 200 may comprise multiplenetwork stacks, for example 267 and 267′, and the first transport layerconnection may be established or terminated at one network stack 267,and the second transport layer connection on the second network stack267′. For example, one network stack may be for receiving andtransmitting network packet on a first network, and another networkstack for receiving and transmitting network packets on a secondnetwork. In one embodiment, the network stack 267 comprises a buffer 243for queuing one or more network packets for transmission by theappliance 200.

As shown in FIG. 2, the kernel space 204 includes the cache manager 232,a high-speed layer 2-7 integrated packet engine 240, an encryptionengine 234, a policy engine 236 and multi-protocol compression logic238. Running these components or processes 232, 240, 234, 236 and 238 inkernel space 204 or kernel mode instead of the user space 202 improvesthe performance of each of these components, alone and in combination.Kernel operation means that these components or processes 232, 240, 234,236 and 238 run in the core address space of the operating system of thedevice 200. For example, running the encryption engine 234 in kernelmode improves encryption performance by moving encryption and decryptionoperations to the kernel, thereby reducing the number of transitionsbetween the memory space or a kernel thread in kernel mode and thememory space or a thread in user mode. For example, data obtained inkernel mode may not need to be passed or copied to a process or threadrunning in user mode, such as from a kernel level data structure to auser level data structure. In another aspect, the number of contextswitches between kernel mode and user mode are also reduced.Additionally, synchronization of and communications between any of thecomponents or processes 232, 240, 235, 236 and 238 can be performed moreefficiently in the kernel space 204.

In some embodiments, any portion of the components 232, 240, 234, 236and 238 may run or operate in the kernel space 204, while other portionsof these components 232, 240, 234, 236 and 238 may run or operate inuser space 202. In one embodiment, the appliance 200 uses a kernel-leveldata structure providing access to any portion of one or more networkpackets, for example, a network packet comprising a request from aclient 102 or a response from a server 106. In some embodiments, thekernel-level data structure may be obtained by the packet engine 240 viaa transport layer driver interface or filter to the network stack 267.The kernel-level data structure may comprise any interface and/or dataaccessible via the kernel space 204 related to the network stack 267,network traffic or packets received or transmitted by the network stack267. In other embodiments, the kernel-level data structure may be usedby any of the components or processes 232, 240, 234, 236 and 238 toperform the desired operation of the component or process. In oneembodiment, a component 232, 240, 234, 236 and 238 is running in kernelmode 204 when using the kernel-level data structure, while in anotherembodiment, the component 232, 240, 234, 236 and 238 is running in usermode when using the kernel-level data structure. In some embodiments,the kernel-level data structure may be copied or passed to a secondkernel-level data structure, or any desired user-level data structure.

The cache manager 232 may comprise software, hardware or any combinationof software and hardware to provide cache access, control and managementof any type and form of content, such as objects or dynamicallygenerated objects served by the originating servers 106. The data,objects or content processed and stored by the cache manager 232 maycomprise data in any format, such as a markup language, or communicatedvia any protocol. In some embodiments, the cache manager 232 duplicatesoriginal data stored elsewhere or data previously computed, generated ortransmitted, in which the original data may require longer access timeto fetch, compute or otherwise obtain relative to reading a cache memoryelement. Once the data is stored in the cache memory element, future usecan be made by accessing the cached copy rather than refetching orrecomputing the original data, thereby reducing the access time. In someembodiments, the cache memory element nat comprise a data object inmemory 264 of device 200. In other embodiments, the cache memory elementmay comprise memory having a faster access time than memory 264. Inanother embodiment, the cache memory element may comrpise any type andform of storage element of the device 200, such as a portion of a harddisk. In some embodiments, the processing unit 262 may provide cachememory for use by the cache manager 232. In yet further embodiments, thecache manager 232 may use any portion and combination of memory,storage, or the processing unit for caching data, objects, and othercontent.

Furthermore, the cache manager 232 includes any logic, functions, rules,or operations to perform any embodiments of the techniques of theappliance 200 described herein. For example, the cache manager 232includes logic or functionality to invalidate objects based on theexpiration of an invalidation time period or upon receipt of aninvalidation command from a client 102 or server 106. In someembodiments, the cache manager 232 may operate as a program, service,process or task executing in the kernel space 204, and in otherembodiments, in the user space 202. In one embodiment, a first portionof the cache manager 232 executes in the user space 202 while a secondportion executes in the kernel space 204. In some embodiments, the cachemanager 232 can comprise any type of general purpose processor (GPP), orany other type of integrated circuit, such as a Field Programmable GateArray (FPGA), Programmable Logic Device (PLD), or Application SpecificIntegrated Circuit (ASIC).

The policy engine 236 may include, for example, an intelligentstatistical engine or other programmable application(s). In oneembodiment, the policy engine 236 provides a configuration mechanism toallow a user to identifying, specify, define or configure a cachingpolicy. Policy engine 236, in some embodiments, also has access tomemory to support data structures such as lookup tables or hash tablesto enable userselected caching policy decisions. In other embodiments,the policy engine 236 may comprise any logic, rules, functions oroperations to determine and provide access, control and management ofobjects, data or content being cached by the appliance 200 in additionto access, control and management of security, network traffic, networkaccess, compression or any other function or operation performed by theappliance 200. Further examples of specific caching policies are furtherdescribed herein.

The encryption engine 234 comprises any logic, business rules, functionsor operations for handling the processing of any security relatedprotocol, such as SSL or TLS, or any function related thereto. Forexample, the encryption engine 234 encrypts and decrypts networkpackets, or any portion thereof, communicated via the appliance 200. Theencryption engine 234 may also setup or establish SSL or TLS connectionson behalf of the client 102 a-102 n, server 106 a-106 n, or appliance200. As such, the encryption engine 234 provides offloading andacceleration of SSL processing. In one embodiment, the encryption engine234 uses a tunneling protocol to provide a virtual private networkbetween a client 102 a-102 n and a server 106 a-106 n. In someembodiments, the encryption engine 234 is in communication with theEncryption processor 260. In other embodiments, the encryption engine234 comprises executable instructions running on the Encryptionprocessor 260.

The multi-protocol compression engine 238 comprises any logic, businessrules, function or operations for compressing one or more protocols of anetwork packet, such as any of the protocols used by the network stack267 of the device 200. In one embodiment, multi-protocol compressionengine 238 compresses bi-directionally between clients 102 a-102 n andservers 106 a-106 n any TCP/IP based protocol, including MessagingApplication Programming Interface (MAPI) (email), File Transfer Protocol(FTP), HyperText Transfer Protocol (HTTP), Common Internet File System(CIFS) protocol (file transfer), Independent Computing Architecture(ICA) protocol, Remote Desktop Protocol (RDP), Wireless ApplicationProtocol (WAP), Mobile IP protocol, and Voice Over IP (VoIP) protocol.In other embodiments, multi-protocol compression engine 238 providescompression of Hypertext Markup Language (HTML) based protocols and insome embodiments, provides compression of any markup languages, such asthe Extensible Markup Language (XML). In one embodiment, themulti-protocol compression engine 238 provides compression of anyhigh-performance protocol, such as any protocol designed for appliance200 to appliance 200 communications. In another embodiment, themulti-protocol compression engine 238 compresses any payload of or anycommunication using a modified transport control protocol, such asTransaction TCP (T/TCP), TCP with selection acknowledgements (TCP-SACK),TCP with large windows (TCP-LW), a congestion prediction protocol suchas the TCP-Vegas protocol, and a TCP spoofing protocol.

As such, the multi-protocol compression engine 238 acceleratesperformance for users accessing applications via desktop clients, e.g.,Microsoft Outlook and non-Web thin clients, such as any client launchedby popular enterprise applications like Oracle, SAP and Siebel, and evenmobile clients, such as the Pocket PC. In some embodiments, themulti-protocol compression engine 238 by executing in the kernel mode204 and integrating with packet processing engine 240 accessing thenetwork stack 267 is able to compress any of the protocols carried bythe TCP/IP protocol, such as any application layer protocol.

High speed layer 2-7 integrated packet engine 240, also generallyreferred to as a packet processing engine or packet engine, isresponsible for managing the kernel-level processing of packets receivedand transmitted by appliance 200 via network ports 266. The high speedlayer 2-7 integrated packet engine 240 may comprise a buffer for queuingone or more network packets during processing, such as for receipt of anetwork packet or transmission of a network packer. Additionally, thehigh speed layer 2-7 integrated packet engine 240 is in communicationwith one or more network stacks 267 to send and receive network packetsvia network ports 266. The high speed layer 2-7 integrated packet engine240 works in conjunction with encryption engine 234, cache manager 232,policy engine 236 and multi-protocol compression logic 238. Inparticular, encryption engine 234 is configured to perform SSLprocessing of packets, policy engine 236 is configured to performfunctions related to traffic management such as request-level contentswitching and request-level cache redirection, and multi-protocolcompression logic 238 is configured to perform functions related tocompression and decompression of data.

The high speed layer 2-7 integrated packet engine 240 includes a packetprocessing timer 242. In one embodiment, the packet processing timer 242provides one or more time intervals to trigger the processing ofincoming, i.e., received, or outgoing, i.e., transmitted, networkpackets. In some embodiments, the high speed layer 2-7 integrated packetengine 240 processes network packets responsive to the timer 242. Thepacket processing timer 242 provides any type and form of signal to thepacket engine 240 to notify, trigger, or communicate a time relatedevent, interval or occurrence. In many embodiments, the packetprocessing timer 242 operates in the order of milliseconds, such as forexample 100 ms, 50 ms or 25 ms. For example, in some embodiments, thepacket processing timer 242 provides time intervals or otherwise causesa network packet to be processed by the high speed layer 2-7 integratedpacket engine 240 at a 10 ms time interval, while in other embodiments,at a 5 ms time interval, and still yet in further embodiments, as shortas a 3, 2, or 1 ms time interval. The high speed layer 2-7 integratedpacket engine 240 may be interfaced, integrated or in communication withthe encryption engine 234, cache manager 232, policy engine 236 andmulti-protocol compression engine 238 during operation. As such, any ofthe logic, functions, or operations of the encryption engine 234, cachemanager 232, policy engine 236 and multi-protocol compression logic 238may be performed responsive to the packet processing timer 242 and/orthe packet engine 240. Therefore, any of the logic, functions, oroperations of the encryption engine 234, cache manager 232, policyengine 236 and multi-protocol compression logic 238 may be performed atthe granularity of time intervals provided via the packet processingtimer 242, for example, at a time interval of less than or equal to 10ms. For example, in one embodiment, the cache manager 232 may performinvalidation of any cached objects responsive to the high speed layer2-7 integrated packet engine 240 and/or the packet processing timer 242.In another embodiment, the expiry or invalidation time of a cachedobject can be set to the same order of granularity as the time intervalof the packet processing timer 242, such as at every 10 ms

In contrast to kernel space 204, user space 202 is the memory area orportion of the operating system used by user mode applications orprograms otherwise running in user mode. A user mode application may notaccess kernel space 204 directly and uses service calls in order toaccess kernel services. As shown in FIG. 2, user space 202 of appliance200 includes a graphical user interface (GUI) 210, a command lineinterface (CLI) 212, shell services 214, health monitoring program 216,and daemon services 218. GUI 210 and CLI 212 provide a means by which asystem administrator or other user can interact with and control theoperation of appliance 200, such as via the operating system of theappliance 200 and either is user space 202 or kernel space 204. The GUI210 may be any type and form of graphical user interface and may bepresented via text, graphical or otherwise, by any type of program orapplication, such as a browser. The CLI 212 may be any type and form ofcommand line or text-based interface, such as a command line provided bythe operating system. For example, the CLI 212 may comprise a shell,which is a tool to enable users to interact with the operating system.In some embodiments, the CLI 212 may be provided via a bash, csh, tcsh,or ksh type shell. The shell services 214 comprises the programs,services, tasks, processes or executable instructions to supportinteraction with the appliance 200 or operating system by a user via theGUI 210 and/or CLI 212.

Health monitoring program 216 is used to monitor, check, report andensure that network systems are functioning properly and that users arereceiving requested content over a network. Health monitoring program216 comprises one or more programs, services, tasks, processes orexecutable instructions to provide logic, rules, functions or operationsfor monitoring any activity of the appliance 200. In some embodiments,the health monitoring program 216 intercepts and inspects any networktraffic passed via the appliance 200. In other embodiments, the healthmonitoring program 216 interfaces by any suitable means and/ormechanisms with one or more of the following: the encryption engine 234,cache manager 232, policy engine 236, multi-protocol compression logic238, packet engine 240, daemon services 218, and shell services 214. Assuch, the health monitoring program 216 may call any applicationprogramming interface (API) to determine a state, status, or health ofany portion of the appliance 200. For example, the health monitoringprogram 216 may ping or send a status inquiry on a periodic basis tocheck if a program, process, service or task is active and currentlyrunning. In another example, the health monitoring program 216 may checkany status, error or history logs provided by any program, process,service or task to determine any condition, status or error with anyportion of the appliance 200.

Daemon services 218 are programs that run continuously or in thebackground and handle periodic service requests received by appliance200. In some embodiments, a daemon service may forward the requests toother programs or processes, such as another daemon service 218 asappropriate. As known to those skilled in the art, a daemon service 218may run unattended to perform continuous or periodic system widefunctions, such as network control, or to perform any desired task. Insome embodiments, one or more daemon services 218 run in the user space202, while in other embodiments, one or more daemon services 218 run inthe kernel space.

Referring now to FIG. 2B, another embodiment of the appliance 200 isdepicted. In brief overview, the appliance 200 provides one or more ofthe following services, functionality or operations: SSL VPNconnectivity 280, switching/load balancing 284, Domain Name Serviceresolution 286, acceleration 288 and an application firewall 290 forcommunications between one or more clients 102 and one or more servers106. In one embodiment, the appliance 200 comprises any of the networkdevices manufactured by Citrix Systems, Inc. of Ft. Lauderdale Fla.,referred to as Citrix NetScaler devices. Each of the servers 106 mayprovide one or more network related services 270 a-270 n (referred to asservices 270). For example, a server 106 may provide an http service270. The appliance 200 comprises one or more virtual servers or virtualinternet protocol servers, referred to as a vServer, VIP server, or justVIP 275 a-275 n (also referred herein as vServer 275). The vServer 275receives, intercepts or otherwise processes communications between aclient 102 and a server 106 in accordance with the configuration andoperations of the appliance 200.

The vServer 275 may comprise software, hardware or any combination ofsoftware and hardware. The vServer 275 may comprise any type and form ofprogram, service, task, process or executable instructions operating inuser mode 202, kernel mode 204 or any combination thereof in theappliance 200. The vServer 275 includes any logic, functions, rules, oroperations to perform any embodiments of the techniques describedherein, such as SSL VPN 280, switching/load balancing 284, Domain NameService resolution 286, acceleration 288 and an application firewall290. In some embodiments, the vServer 275 establishes a connection to aservice 270 of a server 106. The service 275 may comprise any program,application, process, task or set of executable instructions capable ofconnecting to and communicating to the appliance 200, client 102 orvServer 275. For example, the service 275 may comprise a web server,http server, ftp, email or database server. In some embodiments, theservice 270 is a daemon process or network driver for listening,receiving and/or sending communications for an application, such asemail, database or an enterprise application. In some embodiments, theservice 270 may communicate on a specific IP address, or IP address andport.

In some embodiments, the vServer 275 applies one or more policies of thepolicy engine 236 to network communications between the client 102 andserver 106. In one embodiment, the policies are associated with aVServer 275. In another embodiment, the policies are based on a user, ora group of users. In yet another embodiment, a policy is global andapplies to one or more vServers 275 a-275 n, and any user or group ofusers communicating via the appliance 200. In some embodiments, thepolicies of the policy engine have conditions upon which the policy isapplied based on any content of the communication, such as internetprotocol address, port, protocol type, header or fields in a packet, orthe context of the communication, such as user, group of the user,vServer 275, transport layer connection, and/or identification orattributes of the client 102 or server 106.

In other embodiments, the appliance 200 communicates or interfaces withthe policy engine 236 to determine authentication and/or authorizationof a remote user or a remote client 102 to access the computingenvironment 15, application, and/or data file from a server 106. Inanother embodiment, the appliance 200 communicates or interfaces withthe policy engine 236 to determine authentication and/or authorizationof a remote user or a remote client 102 to have the application deliverysystem 190 deliver one or more of the computing environment 15,application, and/or data file. In yet another embodiment, the appliance200 establishes a VPN or SSL VPN connection based on the policy engine's236 authentication and/or authorization of a remote user or a remoteclient 103 In one embodiment, the appliance 102 controls the flow ofnetwork traffic and communication sessions based on policies of thepolicy engine 236. For example, the appliance 200 may control the accessto a computing environment 15, application or data file based on thepolicy engine 236.

In some embodiments, the vServer 275 establishes a transport layerconnection, such as a TCP or UDP connection with a client 102 via theclient agent 120. In one embodiment, the vServer 275 listens for andreceives communications from the client 102. In other embodiments, thevServer 275 establishes a transport layer connection, such as a TCP orUDP connection with a client server 106. In one embodiment, the vServer275 establishes the transport layer connection to an internet protocoladdress and port of a server 270 running on the server 106. In anotherembodiment, the vServer 275 associates a first transport layerconnection to a client 102 with a second transport layer connection tothe server 106. In some embodiments, a vServer 275 establishes a pool oftranport layer connections to a server 106 and multiplexes clientrequests via the pooled transport layer connections.

In some embodiments, the appliance 200 provides a SSL VPN connection 280between a client 102 and a server 106. For example, a client 102 on afirst network 102 requests to establish a connection to a server 106 ona second network 104′. In some embodiments, the second network 104′ isnot routable from the first network 104. In other embodiments, theclient 102 is on a public network 104 and the server 106 is on a privatenetwork 104′, such as a corporate network. In one embodiment, the clientagent 120 intercepts communications of the client 102 on the firstnetwork 104, encrypts the communications, and transmits thecommunications via a first transport layer connection to the appliance200. The appliance 200 associates the first transport layer connectionon the first network 104 to a second transport layer connection to theserver 106 on the second network 104. The appliance 200 receives theintercepted communication from the client agent 102, decrypts thecommunications, and transmits the communication to the server 106 on thesecond network 104 via the second transport layer connection. The secondtransport layer connection may be a pooled transport layer connection.As such, the appliance 200 provides an end-to-end secure transport layerconnection for the client 102 between the two networks 104, 104′.

In one embodiment, the appliance 200 hosts an intranet internet protocolor intranetIP 282 address of the client 102 on the virtual privatenetwork 104. The client 102 has a local network identifier, such as aninternet protocol (IP) address and/or host name on the first network104. When connected to the second network 104′ via the appliance 200,the appliance 200 establishes, assigns or otherwise provides anIntranetIP, which is network identifier, such as IP address and/or hostname, for the client 102 on the second network 104′. The appliance 200listens for and receives on the second or private network 104′ for anycommunications directed towards the client 102 using the client'sestablished IntranetIP 282. In one embodiment, the appliance 200 acts asor on behalf of the client 102 on the second private network 104. Forexample, in another embodiment, a vServer 275 listens for and respondsto communications to the IntranetIP 282 of the client 102. In someembodiments, if a computing device 100 on the second network 104′transmits a request, the appliance 200 processes the request as if itwere the client 102. For example, the appliance 200 may respond to aping to the client's IntranetIP 282. In another example, the appliancemay establish a connection, such as a TCP or UDP connection, withcomputing device 100 on the second network 104 requesting a connectionwith the client's IntranetIP 282.

In some embodiments, the appliance 200 provides one or more of thefollowing acceleration techniques 288 to communications between theclient 102 and server 106: 1) compression; 2) decompression; 3)Transmission Control Protocol pooling; 4) Transmission Control Protocolmultiplexing; 5) Transmission Control Protocol buffering; and 6)caching.

In one embodiment, the appliance 200 relieves servers 106 of much of theprocessing load caused by repeatedly opening and closing transportlayers connections to clients 102 by opening one or more transport layerconnections with each server 106 and maintaining these connections toallow repeated data accesses by clients via the Internet. This techniqueis referred to herein as “connection pooling”.

In some embodiments, in order to seamlessly splice communications from aclient 102 to a server 106 via a pooled transport layer connection, theappliance 200 translates or multiplexes communications by modifyingsequence number and acknowledgment numbers at the transport layerprotocol level. This is referred to as “connection multiplexing”. Insome embodiments, no application layer protocol interaction is required.For example, in the case of an in-bound packet (that is, a packetreceived from a client 102), the source network address of the packet ischanged to that of an output port of appliance 200, and the destinationnetwork address is changed to that of the intended server. In the caseof an outbound packet (that is, one received from a server 106), thesource network address is changed from that of the server 106 to that ofan output port of appliance 200 and the destination address is changedfrom that of appliance 200 to that of the requesting client 102. Thesequence numbers and acknowledgment numbers of the packet are alsotranslated to sequence numbers and acknowledgement expected by theclient 102 on the appliance's 200 transport layer connection to theclient 102. In some embodiments, the packet checksum of the transportlayer protocol is recalculated to account for these translations.

In another embodiment, the appliance 200 provides switching orload-balancing functionality 284 for communications between the client102 and server 106. In some embodiments, the appliance 200 distributestraffic and directs client requests to a server 106 based on layer 4 orapplication-layer request data. In one embodiment, although the networklayer or layer 2 of the network packet identifies a destination server106, the appliance 200 determines the server 106 to distribute thenetwork packet by application information and data carried as payload ofthe transport layer packet. In one embodiment, the health monitoringprograms 216 of the appliance 200 monitor the health of servers todetermine the server 106 for which to distribute a client's request. Insome embodiments, if the appliance 200 detects a server 106 is notavailable or has a load over a predetermined threshold, the appliance200 can direct or distribute client requests to another server 106.

In some embodiments, the appliance 200 acts as a Domain Name Service(DNS) resolver or otherwise provides resolution of a DNS request fromclients 102. In some embodiments, the appliance intercepts' a DNSrequest transmitted by the client 102. In one embodiment, the appliance200 responds to a client's DNS request with an IP address of or hostedby the appliance 200. In this embodiment, the client 102 transmitsnetwork communication for the domain name to the appliance 200. Inanother embodiment, the appliance 200 responds to a client's DNS requestwith an IP address of or hosted by a second appliance 200′. In someembodiments, the appliance 200 responds to a client's DNS request withan IP address of a server 106 determined by the appliance 200.

In yet another embodiment, the appliance 200 provides applicationfirewall functionality 290 for communications between the client 102 andserver 106. In one embodiment, the policy engine 236 provides rules fordetecting and blocking illegitimate requests. In some embodiments, theapplication firewall 290 protects against denial of service (DoS)attacks. In other embodiments, the appliance inspects the content ofintercepted requests to identify and block application-based attacks. Insome embodiments, the rules/policy engine 236 comprises one or moreapplication firewall or security control policies for providingprotections against various classes and types of web or Internet basedvulnerabilities, such as one or more of the following: 1) bufferoverflow, 2) CGI-BIN parameter manipulation, 3) form/hidden fieldmanipulation, 4) forceful browsing, 5) cookie or session poisoning, 6)broken access control list (ACLs) or weak passwords, 7) cross-sitescripting (XSS), 8) command injection, 9) SQL injection, 10) errortriggering sensitive information leak, 11) insecure use of cryptography,12) server misconfiguration, 13) back doors and debug options, 14)website defacement, 15) platform or operating systems vulnerabilities,and 16) zero-day exploits. In an embodiment, the application firewall290 provides HTML form field protection in the form of inspecting oranalyzing the network communication for one or more of the following: 1)required fields are returned, 2) no added field allowed, 3) read-onlyand hidden field enforcement, 4) drop-down list and radio button fieldconformance, and 5) form-field max-length enforcement. In someembodiments, the application firewall 290 ensures cookies are notmodified. In other embodiments, the application firewall 290 protectsagainst forceful browsing by enforcing legal URLs.

In still yet other embodiments, the application firewall 290 protectsany confidential information contained in the network communication. Theapplication firewall 290 may inspect or analyze any networkcommunication in accordance with the rules or polices of the engine 236to identify any confidential information in any field of the networkpacket. In some embodiments, the application firewall 290 identifies inthe network communication one or more occurrences of a credit cardnumber, password, social security number, name, patient code, contactinformation, and age. The encoded portion of the network communicationmay comprise these occurrences or the confidential information. Based onthese occurrences, in one embodiment, the application firewall 290 maytake a policy action on the network communication, such as preventtransmission of the network communication. In another embodiment, theapplication firewall 290 may rewrite, remove or otherwise mask suchidentified occurrence or confidential information.

C. Client Agent

Referring now to FIG. 3, an embodiment of the client agent 120 isdepicted. The client 102 includes a client agent 120 for establishingand exchanging communications with the appliance 200 and/or server 106via a network 104. In brief overview, the client 102 operates oncomputing device 100 having an operating system with a kernel mode 302and a user mode 303, and a network stack 310 with one or more layers 310a-310 b. The client 102 may have installed and/or execute one or moreapplications. In some embodiments, one or more applications maycommunicate via the network stack 310 to a network 104. One of theapplications, such as a web browser, may also include a first program322. For example, the first program 322 may be used in some embodimentsto install and/or execute the client agent 120, or any portion thereof.The client agent 120 includes an interception mechanism, or interceptor350, for intercepting network communications from the network stack 310from the one or more applications.

The network stack 310 of the client 102 may comprise any type and formof software, or hardware, or any combinations thereof, for providingconnectivity to and communications with a network. In one embodiment,the network stack 310 comprises a software implementation for a networkprotocol suite. The network stack 310 may comprise one or more networklayers, such as any networks layers of the Open Systems Interconnection(OSI) communications model as those skilled in the art recognize andappreciate. As such, the network stack 310 may comprise any type andform of protocols for any of the following layers of the OSI model: 1)physical link layer, 2) data link layer, 3) network layer, 4) transportlayer, 5) session layer, 6) presentation layer, and 7) applicationlayer. In one embodiment, the network stack 310 may comprise a transportcontrol protocol (TCP) over the network layer protocol of the internetprotocol (IP), generally referred to as TCP/IP. In some embodiments, theTCP/IP protocol may be carried over the Ethernet protocol, which maycomprise any of the family of IEEE wide-area-network (WAN) orlocal-area-network (LAN) protocols, such as those protocols covered bythe IEEE 802.3. In some embodiments, the network stack 310 comprises anytype and form of a wireless protocol, such as IEEE 802.11 and/or mobileinternet protocol.

In view of a TCP/IP based network, any TCP/IP based protocol may beused, including Messaging Application Programming Interface (MAPI)(email), File Transfer Protocol (FTP), HyperText Transfer Protocol(HTTP), Common Internet File System (CIFS) protocol (file transfer),Independent Computing Architecture (ICA) protocol, Remote DesktopProtocol (RDP), Wireless Application Protocol (WAP), Mobile IP protocol,and Voice Over IP (VoIP) protocol. In another embodiment, the networkstack 310 comprises any type and form of transport control protocol,such as a modified transport control protocol, for example a TransactionTCP (T/TCP), TCP with selection acknowledgements (TCP-SACK), TCP withlarge windows (TCP-LW), a congestion prediction protocol such as theTCP-Vegas protocol, and a TCP spoofing protocol. In other embodiments,any type and form of user datagram protocol (UDP), such as UDP over IP,may be used by the network stack 310, such as for voice communicationsor real-time data communications.

Furthermore, the network stack 310 may include one or more networkdrivers supporting the one or more layers, such as a TCP driver or anetwork layer driver. The network drivers may be included as part of theoperating system of the computing device 100 or as part of any networkinterface cards or other network access components of the computingdevice 100. In some embodiments, any of the network drivers of thenetwork stack 310 may be customized, modified or adapted to provide acustom or modified portion of the network stack 310 in support of any ofthe techniques described herein. In other embodiments, the accelerationprogram 120 is designed and constructed to operate with or work inconjunction with the network stack 310 installed or otherwise providedby the operating system of the client 102.

The network stack 310 comprises any type and form of interfaces forreceiving, obtaining, providing or otherwise accessing any informationand data related to network communications of the client 102. In oneembodiment, an interface to the network stack 310 comprises anapplication programming interface (API). The interface may also compriseany function call, hooking or filtering mechanism, event or call backmechanism, or any type of interfacing technique. The network stack 310via the interface may receive or provide any type and form of datastructure, such as an object, related to functionality or operation ofthe network stack 310. For example, the data structure may compriseinformation and data related to a network packet or one or more networkpackets. In some embodiments, the data structure comprises a portion ofthe network packet processed at a protocol layer of the network stack310, such as a network packet of the transport layer. In someembodiments, the data structure 325 comprises a kernel-level datastructure, while in other embodiments, the data structure 325 comprisesa user-mode data structure. A kernel-level data structure may comprise adata structure obtained or related to a portion of the network stack 310operating in kernel-mode 302, or a network driver or other softwarerunning in kernel-mode 302, or any data structure obtained or receivedby a service, process, task, thread or other executable instructionsrunning or operating in kernel-mode of the operating system.

Additionally, some portions of the network stack 310 may execute oroperate in kernel-mode 302, for example, the data link or network layer,while other portions execute or operate in user-mode 303, such as anapplication layer of the network stack 310. For example, a first portion310 a of the network stack may provide user-mode access to the networkstack 310 to an application while a second portion 310 a of the networkstack 310 provides access to a network. In some embodiments, a firstportion 310 a of the network stack may comprise one or more upper layersof the network stack 310, such as any of layers 5-7. In otherembodiments, a second portion 310 b of the network stack 310 comprisesone or more lower layers, such as any of layers 1-4. Each of the firstportion 310 a and second portion 310 b of the network stack 310 maycomprise any portion of the network stack 310, at any one or morenetwork layers, in user-mode 203, kernel-mode, 202, or combinationsthereof, or at any portion of a network layer or interface point to anetwork layer or any portion of or interface point to the user-mode 203and kernel-mode 203.

The interceptor 350 may comprise software, hardware, or any combinationof software and hardware. In one embodiment, the interceptor 350intercept a network communication at any point in the network stack 310,and redirects or transmits the network communication to a destinationdesired, managed or controlled by the interceptor 350 or client agent120. For example, the interceptor 350 may intercept a networkcommunication of a network stack 310 of a first network and transmit thenetwork communication to the appliance 200 for transmission on a secondnetwork 104. In some embodiments, the interceptor 350 comprises any typeinterceptor 350 comprises a driver, such as a network driver constructedand designed to interface and work with the network stack 310. In someembodiments, the client agent 120 and/or interceptor 350 operates at oneor more layers of the network stack 310, such as at the transport layer.In one embodiment, the interceptor 350 comprises a filter driver,hooking mechanism, or any form and type of suitable network driverinterface that interfaces to the transport layer of the network stack,such as via the transport driver interface (TDI). In some embodiments,the interceptor 350 interfaces to a first protocol layer, such as thetransport layer and another protocol layer, such as any layer above thetransport protocol layer, for example, an application protocol layer. Inone embodiment, the interceptor 350 may comprise a driver complying withthe Network Driver Interface Specification (NDIS), or a NDIS driver. Inanother embodiment, the interceptor 350 may comprise a min-filter or amini-port driver. In one embodiment, the interceptor 350, or portionthereof, operates in kernel-mode 202. In another embodiment, theinterceptor 350, or portion thereof, operates in user-mode 203. In someembodiments, a portion of the interceptor 350 operates in kernel-mode202 while another portion of the interceptor 350 operates in user-mode203. In other embodiments, the client agent 120 operates in user-mode203 but interfaces via the interceptor 350 to a kernel-mode driver,process, service, task or portion of the operating system, such as toobtain a kernel-level data structure 225. In further embodiments, theinterceptor 350 is a user-mode application or program, such asapplication.

In one embodiment, the interceptor 350 intercepts any transport layerconnection requests. In these embodiments, the interceptor 350 executetransport layer application programming interface (API) calls to set thedestination information, such as destination IP address and/or port to adesired location for the location. In this manner, the interceptor 350intercepts and redirects the transport layer connection to a IP addressand port controlled or managed by the interceptor 350 or client agent120. In one embodiment, the interceptor 350 sets the destinationinformation for the connection to a local IP address and port of theclient 102 on which the client agent 120 is listening. For example, theclient agent 120 may comprise a proxy service listening on a local IPaddress and port for redirected transport layer communications. In someembodiments, the client agent 120 then communicates the redirectedtransport layer communication to the appliance 200.

In some embodiments, the interceptor 350 intercepts a Domain NameService (DNS) request. In one embodiment, the client agent 120 and/orinterceptor 350 resolves the DNS request. In another embodiment, theinterceptor transmits the intercepted DNS request to the appliance 200for DNS resolution. In one embodiment, the appliance 200 resolves theDNS request and communicates the DNS response to the client agent 120.In some embodiments, the appliance 200 resolves the DNS request viaanother appliance 200′ or a DNS server 106.

In yet another embodiment, the client agent 120 may comprise two agents120 and 120′. In one embodiment, a first agent 120 may comprise aninterceptor 350 operating at the network layer of the network stack 310.In some embodiments, the first agent 120 intercepts network layerrequests such as Internet Control Message Protocol (ICMP) requests(e.g., ping and traceroute). In other embodiments, the second agent 120′may operate at the transport layer and intercept transport layercommunications. In some embodiments, the first agent 120 interceptscommunications at one layer of the network stack 210 and interfaces withor communicates the intercepted communication to the second agent 120′.

The client agent 120 and/or interceptor 350 may operate at or interfacewith a protocol layer in a manner transparent to any other protocollayer of the network stack 310. For example, in one embodiment, theinterceptor 350 operates or interfaces with the transport layer of thenetwork stack 310 transparently to any protocol layer below thetransport layer, such as the network layer, and any protocol layer abovethe transport layer, such as the session, presentation or applicationlayer protocols. This allows the other protocol layers of the networkstack 310 to operate as desired and without modification for using theinterceptor 350. As such, the client agent 120 and/or interceptor 350can interface with the transport layer to secure, optimize, accelerate,route or load-balance any communications provided via any protocolcarried by the transport layer, such as any application layer protocolover TCP/IP.

Furthermore, the client agent 120 and/or interceptor may operate at orinterface with the network stack 310 in a manner transparent to anyapplication, a user of the client 102, and any other computing device,such as a server, in communications with the client 102. The clientagent 120 and/or interceptor 350 may be installed and/or executed on theclient 102 in a manner without modification of an application. In someembodiments, the user of the client 102 or a computing device incommunications with the client 102 are not aware of the existence,execution or operation of the client agent 120 and/or interceptor 350.As such, in some embodiments, the client agent 120 and/or interceptor350 is installed, executed, and/or operated transparently to anapplication, user of the client 102, another computing device, such as aserver, or any of the protocol layers above and/or below the protocollayer interfaced to by the interceptor 350.

The client agent 120 includes an acceleration program 302, a streamingclient 306, and/or a collection agent 304. In one embodiment, the clientagent 120 comprises an Independent Computing Architecture (ICA) client,or any portion thereof, developed by Citrix Systems, Inc. of FortLauderdale, Fla., and is also referred to as an ICA client. In someembodiments, the client 120 comprises an application streaming client306 for streaming an application from a server 106 to a client 102. Insome embodiments, the client agent 120 comprises an acceleration program302 for accelerating communications between client 102 and server 106.In another embodiment, the client agent 120 includes a collection agent304 for performing end-point detection/scanning and collecting end-pointinformation for the appliance 200 and/or server 106.

In some embodiments, the acceleration program 302 comprises aclient-side acceleration program for performing one or more accelerationtechniques to accelerate, enhance or otherwise improve a client'scommunications with and/or access to a server 106, such as accessing anapplication provided by a server 106. The logic, functions, and/oroperations of the executable instructions of the acceleration program302 may perform one or more of the following acceleration techniques: 1)multi-protocol compression, 2) transport control protocol pooling, 3)transport control protocol multiplexing, 4) transport control protocolbuffering, and 5) caching via a cache manager Additionally, theacceleration program 302 may perform encryption and/or decryption of anycommunications received and/or transmitted by the client 102. In someembodiments, the acceleration program 302 performs one or more of theacceleration techniques in an integrated manner or fashion.Additionally, the acceleration program 302 can perform compression onany of the protocols, or multiple-protocols, carried as payload ofnetwork packet of the transport layer protocol The streaming client 306comprises an application, program, process, service, task or executableinstructions for receiving and executing a streamed application from aserver 106. A server 106 may stream one or more application data filesto the streaming client 306 for playing, executing or otherwise causingto be executed the application on the client 102. In some embodiments,the server 106 transmits a set of compressed or packaged applicationdata files to the streaming client 306. In some embodiments, theplurality of application files are compressed and stored on a fileserver within an archive file such as a CAB, ZIP, SIT, TAR, JAR or otherarchive. In one embodiment, the server 106 decompresses, unpackages orunarchives the application files and transmits the files to the client102. In another embodiment, the client 102 decompresses, unpackages orunarchives the application files. The streaming client 306 dynamicallyinstalls the application, or portion thereof, and executes theapplication. In one embodiment, the streaming client 306 may be anexecutable program. In some embodiments, the streaming client 306 may beable to launch another executable program.

The collection agent 304 comprises an application, program, process,service, task or executable instructions for identifying, obtainingand/or collecting information about the client 102. In some embodiments,the appliance 200 transmits the collection agent 304 to the client 102or client agent 120. The collection agent 304 may be configuredaccording to one or more policies of the policy engine 236 of theappliance. In other embodiments, the collection agent 304 transmitscollected information on the client 102 to the appliance 200. In oneembodiment, the policy engine 236 of the appliance 200 uses thecollected information to determine and provide access, authenticationand authorization control of the client's connection to a network 104.

In one embodiment, the collection agent 304 comprises an end-pointdetection and scanning mechanism, which identifies and determines one ormore attributes or characteristics of the client. For example, thecollection agent 304 may identify and determine any one or more of thefollowing client-side attributes: 1) the operating system an/or aversion of an operating system, 2) a service pack of the operatingsystem, 3) a running service, 4) a running process, and 5) a file. Thecollection agent 304 may also identify and determine the presence orversions of any one or more of the following on the client: 1) antivirussoftware, 2) personal firewall software, 3) anti-spam software, and 4)internet security software. The policy engine 236 may have one or morepolicies based on any one or more of the attributes or characteristicsof the client or client-side attributes.

In some embodiments and still referring to FIG. 3, a first program 322may be used to install and/or execute the client agent 120, or portionthereof, such as the interceptor 350, automatically, silently,transparently, or otherwise. In one embodiment, the first program 322comprises a plugin component, such an ActiveX control or Java control orscript that is loaded into and executed by an application. For example,the first program comprises an ActiveX control loaded and run by a webbrowser application, such as in the memory space or context of theapplication. In another embodiment, the first program 322 comprises aset of executable instructions loaded into and run by the application,such as a browser. In one embodiment, the first program 322 comprises adesigned and constructed program to install the client agent 120. Insome embodiments, the first program 322 obtains, downloads, or receivesthe client agent 120 via the network from another computing device. Inanother embodiment, the first program 322 is an installer program or aplug and play manager for installing programs, such as network drivers,on the operating system of the client 102.

Referring now to FIG. 4, one embodiment of a method for using a clientagent 120 operating in a virtual private network environment tointercept HTTP communications is shown. In brief overview, the methodcomprises intercepting at the network layer, by a client agent 120executing on a client, an HTTP request from an application executing onthe client (step 401); modifying the HTTP request (step 403); andtransmitting, via a transport layer connection, the modified HTTPrequest to a network appliance 200 (step 405).

Still referring to FIG. 4, now in greater detail, a client agent 120executing on a client intercepts at the network layer an HTTP requestfrom an application executing on the client (step 401). Thisinterception may be performed by any means, including without limitationthe use of a TDI driver as discussed herein. Although in the embodimentshown, the interception occurs at the network layer, in otherembodiments, the interception may occur at the session layer or thetransport layer. The application may comprise any application using theHTTP protocol, including without limitation web browsers and webapplications.

In some embodiments the interception may be performed transparently tothe user, the application, or both. In some embodiments the interceptionmay be performed transparently to one or more layers of the networkstack above or below the layer at which the interception occurs.

After intercepting at the network layer, by the client agent, an HTTPrequest from an application executing on the client (step 401); theclient agent may modify the HTTP request (step 403).

In some embodiments, the client agent may modify the HTTP request byadding, removing, or modifying a cookie contained within the HTTPrequest. The client agent may add, remove, or modify a cookie in orderto perform any of the functions associated with a client agent describedherein.

In one embodiment, a client agent may add an HTTP cookie comprisingauthentication credentials to be transmitted to a VPN appliance 200 asdescribed herein.

In another embodiment, a client agent may add an HTTP cookie comprisingcaching information. For example, a client agent may add an HTTP cookiecomprising information that the client agent has stored a previousversion of a requested resource. A network appliance receiving theinserted cookie may then transmit only the portions of the requestedresource that have changed since the previously stored version. Onespecific method of caching which may employ this technique will bediscussed beginning at FIG. 7.

In some embodiments, the client agent 120 may modify the HTTP request byadding, removing, or modifying a name-value pair contained in the HTTPrequest. These name-value pairs may be modified in conjunction with anyof the functions performed by the client agent, including acceleration,pooling, caching, and security. In one embodiment, the client agent mayname-value pairs in an HTTP header.

For example, a client agent may modify, add, or remove a value followingthe “connection” HTTP message header, to indicate that the client agentwishes to keep the HTTP connection open rather than closed. This may bedone by inserting a “keep-alive” value, or removing a “close” value.

Or, for example, a client agent may modify, add or remove a valuefollowing a “referrer” HTTP message header for security purposes.Removing the “referrer” variable may be desired to minimize theknowledge website operators can gain about the client's browsinghistory.

Or, for example, a client agent may modify, add, or remove a valuefollowing a “authorization” HTTP message header. The client agent mayinsert or remove security credentials on behalf of the client in orderto provide secure access to resources.

Or, for example, a client agent may modify, add, or remove a valuefollowing a “cache-control.” This may be used to support or enhance anyof the caching features described herein.

In some embodiments, the client agent may add, remove, or modify aname-value pair in a URL specified by the HTTP request, in accordancewith any of the functions described herein. In still other embodiments,the client agent may rewrite the requested URL itself.

In some embodiments, the client agent may further determine a routingdecision based on a URL specified in the HTTP header. For example, if aclient is requesting a URL that corresponds to a file associated with agiven application server, the client agent may route the client requestdirectly to the application server.

After modifying the HTTP request (step 403) the client agent maytransmit, via a transport layer connection, the modified HTTP request toa network appliance 200 (step 405). This transmission may occur via anytransport layer protocols. In one embodiment, the HTTP request may betransmitted via an SSL connection to the network appliance 200. Theclient agent may perform any of the functions described herein on thetransmission of the HTTP request, including acceleration andcompression.

Referring now to FIG. 5, one embodiment of a method for using a clientagent to enable HTTP cookie authentication in non-HTTP communicationsfrom a client is shown. In brief overview, the method comprises:intercepting, by a client agent executing on a client, a connectionrequest from the client (step 501); establishing, by the client agent, atransport layer virtual private network connection with a networkappliance (step 503); transmitting, by the client agent via theestablished connection, an HTTP request comprising an authenticationcookie (step 505); receiving, by the client agent, an HTTP response, theHTTP response comprising an acceptance of the authentication cookie;(step 507) and transmitting, by the client agent via the connection, theconnection request (step 509).

Still referring to FIG. 5, now in greater detail, a client agent 120executing on a client 102 intercepts a connection request from theclient (step 501). This interception may occur via any of the methodsdiscussed herein, including via a TDI driver. The connection request maycomprise a request from the client to open any type of networkconnection, including non-HTTP connections. In one embodiment, theconnection request may comprise a TCP SYN packet.

After intercepting a connection request from the client (step 501) theclient agent may establish a transport layer virtual private networkconnection with a network appliance (step 503). This connection maycomprise any transport layer protocol described herein. In oneembodiment, the transport layer VPN connection may comprise an SSLconnection. In some embodiments, the client agent may utilize apreviously existing SSL VPN connection. In still other embodiments, theclient agent may establish a new connection within a previously existingVPN connection. In these embodiments, the new connection may be pooledor multiplexed with other connections within the existing VPNconnection.

After establishing the transport layer VPN connection (step 503), theclient agent may transmit, via the established connection, an HTTPrequest comprising an authentication cookie (step 505). In someembodiments, the HTTP request may comprise an authentication cookiepreviously transmitted to the client by the network appliance. Forexample, a client agent may establish an SSL VPN connection with anetwork appliance 200, and may receive from the network appliance anauthentication cookie. If the client agent desires to open a secondconnection with the network appliance, the client agent may thenretransmit the received cookie, providing authentication withoutrequiring a second logon procedure.

An authentication cookie may comprise any authentication informationtransmitted via an HTTP request. In one embodiment, the authenticationcookie may comprise an authentication string, which allows the networkappliance to verify the identity of a user of the client. In anotherembodiment, the authentication cookie may comprise an authenticationstring which allows the network appliance to verify a requestcorresponds to a particular user session. In still another embodiment,the authentication cookie may comprise an authentication string whichallows the network appliance to verify a request corresponds to aparticular application session.

In one embodiment, the client agent may ensure that the HTTP requestcomprising the authentication cookie is the first data sent via the newconnection. For example, after the connection is established, the clientagent may transmit an HTTP request “GET URL HTTP/1.1\r\n . . . ”followed by an authentication cookie. In one embodiment, the clientagent may queue any data the client attempts to send following theconnection request until the HTTP request is transmitted. In anotherembodiment, the client agent may queue any data the client attempts tosend following the connection request until an HTTP response is receivedfrom the network appliance.

After transmitting, via the established connection, an HTTP requestcomprising an authentication cookie (step 505); the client agent mayreceive an HTTP response, the HTTP response comprising an acceptance ofthe authentication cookie (step 507).

After receiving the HTTP response comprising an acceptance of theauthentication cookie; (step 507) the client agent may transmit via theestablished connection, the connection request (step 509). The clientagent may then perform any additional steps to service the connectionrequest and establish the requested connection. The client agent maythen transmit any data that had been queued for the requestedconnection.

Referring now to FIG. 6, a method for using a client agent to enablesecure authentication in a virtual private network environment using anHTTP cookie is shown. In brief overview, the method comprises:intercepting, by a client agent executing on a client, an HTTPcommunication comprising a cookie from an appliance on a virtual privatenetwork to the client (step 601); removing, by the client agent, thecookie from the HTTP communication (step 603); storing, by the clientagent, the received cookie (step 605); transmitting, by the clientagent, the modified HTTP communication to an application executing onthe client (step 607); intercepting, by the client agent, an HTTPrequest from the client (step 609); inserting, by the client agent inthe HTTP request, the received cookie (step 611); and transmitting themodified HTTP request to the appliance (step 613).

Still referring to FIG. 6, now in greater detail, a client agent 120executing on a client 102 intercepts an HTTP communication comprising acookie from an appliance on a virtual private network to the client(step 601). This cookie may comprise any authentication credentials,including without limitation user-specific, session-specific, andapplication-specific authentication credentials. In some embodiments,the cookie may be transmitted from the appliance to the client inresponse to a logon request and associated information from the client.The client agent may intercept the communication using any meansdescribed herein, including a TDI driver.

After intercepting the HTTP communication comprising a cookie from anappliance on a virtual private network to the client (step 601); theclient agent may remove the cookie from the HTTP communication (step603). The client agent may delete the cookie from the HTTP response byremoving the name-value pair or pairs in the HTTP header that comprisethe cookie.

In some embodiments, the client agent may also add, remove, or modifyother name-value pairs in the received HTTP header in accordance withany of the embodiments discussed herein. In one embodiment, the clientagent may add, remove, or modify the HTTP header such that anyinformation in the received HTTP header resulting from previous clientagent alterations to an HTTP request is masked from the client. Forexample, a client agent may insert a name-value pair in an HTTP requestidentifying a plurality of versions of the requested resource which arecurrently cached on the client. The client agent may then receive anHTTP response comprising a file consisting of changes from one of theidentified versions, as well as a name-value pair in the HTTP headeridentifying which version was used as the base. The client agent mayremove this name-value pair in addition to assembling the updatedversion such that the caching techniques are transparent to the clientapplication.

After removing, by the client agent, the cookie from the HTTPcommunication (step 603); the client agent may store the received cookie(step 605). The client agent may store the received cookie using anystorage method or device. In one embodiment, the client agent may storethe cookie as a file on disk. In another embodiment, the client agentmay store the cookie in RAM. The client agent may use any methods ofsorting or indexing the stored cookie, including without limitationindexing by user, session, application, appliance, connection, or VPN.

After storing the received cookie (step 605) the client agent may thentransmit the modified HTTP communication to an application executing onthe client (step 607). The modified HTTP communication may betransmitted to the client using any means described herein, including aTDI driver.

After transmitting the modified HTTP communication to an applicationexecuting on the client, the client agent may intercept an HTTP requestfrom the client (step 609). The interception may occur via any of themeans discussed herein, including a TDI driver. The HTTP request may befrom the application the HTTP response was transmitted to, or the HTTPrequest may be from a second application. In some embodiments, theclient agent may intercept HTTP requests from a plurality ofapplications.

After intercepting an HTTP request from the client (step 609) the clientagent may then insert, in the HTTP request, the received cookie (step611). The client agent may insert the HTTP cookie by searching a file,directory, or database for the received cookie, and then inserting thecookie into the request. In some embodiments, the client agent maycontain an HTTP parser such that the client agent can identify thepayload boundary of the HTTP request.

After inserting, in the HTTP request, the received cookie (step 611);the client agent may transmit the modified HTTP request to the appliance(step 613). This transmission may via any method described herein. Insome embodiments, the client agent may then receive an HTTP responsefrom the appliance indicating the cookie is accepted.

In some embodiments, the client agent may provide further cookiemanagement functionality. For example, the client agent may detect whena VPN session has ended, and delete any stored cookies corresponding tothe VPN session.

Referring now to FIGS. 7 through 11, a detailed example of a caching andupdate method is shown which may utilize any of the client cookiemanagement and HTTP aware functionality previously discussed.

Referring now to FIG. 7 one embodiment of a method for creating anefficient update to a previously stored file is shown. Although FIG. 7depicts the method in the context of being performed by a networkappliance 200 and a client 102, the method may be performed by any ofthe computing devices discussed herein either alone or in anycombination. In brief overview, the method comprises: receiving a firstfile comprising a first plurality of sequences of data (step 701);transmitting the first file to a client or client agent (step 703);receiving a second file comprising a second plurality of sequences ofdata (step 709); creating a hash table having a plurality of entries,each of the plurality of entries corresponding to a respective one ofthe first plurality of sequences, and wherein at least two of saidentries correspond to overlapping sequences of data (step 711);computing hash values for said second plurality of sequences of data(step 713); comparing each of the second plurality of sequences of datawith sequences from the first plurality of sequences having the samehash value to determine sequences of data present in both files (step715); storing representations of lengths and locations of said sequencesof data present in both the first and second files (step 717); creatinga third file comprising sequences of data from the second file andrepresentations of locations and lengths of said sequences of datapresent in both the first and second files (step 719); and transmittingthe third file to a client or client agent (step 721).

Still referring to FIG. 7, and now in greater detail, the networkappliance 200 receives a first file comprising a first plurality ofsequences of data (step 701). In some embodiments the first file may bereceived from a network 211′, from a server 205, from a database, orfrom any combination thereof. In some embodiments the first file may beread from a disk or other storage medium, retrieved from a cache, oraccessed from RAM. In other embodiments the first file may be receivedfrom an application or process executing on the network appliance 200.In some embodiments, the first file may comprise a file requested by aclient or client agent.

The first file may comprise sequences of data corresponding to sequencesof bits or bytes comprising the file. The first file may comprise anyfile protocol, including without limitation, HTML, XML, WML, SVG, otherdocument protocols, image file protocols, sound file protocols, videofile protocols, and binary file protocols. In some embodiments the filecomprises a web page or a portion of a web page. In some embodiments thefile comprises any web page that is updated with some frequency,including without limitation a news page, a web application page, a chatroom, a bulletin board, a sports page, an e-mail page, a directorylisting, a tracking page, and a webcam page. After receiving the firstfile, the network appliance 200 may store or cache the first file topermit later retrieval. In some embodiments the network appliance 200may modify said first file in accordance with any of the networkappliance functions described herein.

In some embodiments, after receiving the first file (step 701), thenetwork appliance 200 transmits the first file to a client (step 703).The network appliance 200 may transmit the first file via any of thenetworks, or protocols described herein, and to any of the clients orclient agents described herein. The network appliance 200 may modify thefirst file in accordance with any of the functions performed by thenetwork appliance, including compression, acceleration and encryption.Although FIG. 7 depicts the network appliance 200 transmitting the firstfile immediately after step 701, in other embodiments said transmittalcould occur after any of the steps (steps 705-721) occurring after thenetwork appliance 200 receives the first file (step 701).

In some embodiments, the network appliance 200 may store a record ofsaid transmission. Said record may be stored in any memory element,including a data base or cache. In one embodiment, the network appliance200 may access said cache to determine whether a given file has beenpreviously transmitted to a client. In one embodiment, said records maybe set to expire after a set amount of time. For example, if a networkappliance 200 has information indicating that a given client 102 deletesall files from its cache at the end of each day, the network appliancemay set all records of files transmitted to the client 102 to expire atthe end of each day.

In the embodiment shown, after the network appliance 200 transmits thefirst file to the client 102 (step 703), the client may then receive thefirst file (step 705), display the first file (step 707), and store thefirst file (step 708). The client may perform these steps in accordancewith any of the embodiments described herein.

In the embodiment shown, after the network appliance 200 transmits thefirst file to the client 102 or client agent 120 (step 703), the networkappliance receives a second file comprising a second plurality ofsequences of data (step 709). In other embodiments, the networkappliance 200 may receive the second file (step 709) before or duringthe transmission of the first file to the client (step 703). The secondfile may comprise any of the file types, protocols, web pages andportions of web pages discussed herein. After receiving the second file,the network appliance 200 may store or cache the second file to permitlater retrieval. In some embodiments the network appliance 200 maymodify said second file in accordance with any of the network appliancefunctions described herein.

In some embodiments, the second file may comprise a file requested by aclient agent. In one embodiment, the client agent may transmit a requestto the network appliance for the second file, the request comprisinginformation identifying that the client agent has a stored copy of thefirst file. In some embodiments, this request may be an HTTP request.For example, a client agent may transmit an HTTP request for a news webpage. The client agent may insert in the HTTP request the followingname-value pair “previously-stored-version=826482764” where 826482764may comprise a serial number or timestamp corresponding to a priorversion of the news web page stored earlier (an thus corresponding tothe first file discussed with respect to this figure). The appliance 200may then use this serial number or timestamp to retrieve the first filefrom its own storage.

After receiving the second file comprising a second plurality ofsequences of data (step 709), the network appliance may create a hashtable having a plurality of entries, each of the plurality of entriescorresponding to a respective one of the first plurality of sequences,and wherein at least two of said entries correspond to overlappingsequences of data (step 711). Said hash table may be created accordingto any known hash table algorithm which provides functionality to storesequences of data or references to sequences of data as entries and thenefficiently search said table for entries matching a given sequence. Inother embodiments, the network appliance may create the hash table (step711) before or during receiving the second file (step 709).

In some embodiments, the entries in the hash table may correspond tosequences of data from the first file comprising sequences of bytes. Thesequences of bytes may be of any length. In one embodiment the sequencesare four-byte sequences.

In the embodiment shown, at least two of the hash table entriescorrespond to overlapping sequences of data. Overlapping sequences mayhave any number of bytes in common. For example if the file comprisedthe sequence “abcdefghijklmnop”, examples of overlapping four-bytesequences include “cdef” and “defg” in addition to “cdef” and fghi.” Inone embodiment, the hash table entries correspond to successiveoverlapping byte sequences. For example, if the file comprised thesequence “abcdefg”, a hash table comprising at least two successiveoverlapping four-byte sequences may include entries corresponding to thesequences “abcd” “bcde” “cdef” and “defg”.

In some embodiments, the hash table entries at a given time may onlycorrespond to sequences of data from a given portion or “window” of thefirst file. This allows the size of the hash table to be smaller thanthe hash table might be if the entire file was hashed at once. In someembodiments, only the first X bytes of the first file are hashed, andthen, upon occurrence of some conditions, Y entries are removed from thetable followed by Y more entries being added to the table. In oneembodiment a window size of 64 kilobytes is used, and upon occurrence ofcertain conditions, the window is moved by 32 kilobytes. In thisembodiment, the sequences from the first 64 kilobytes of the first fileare hashed, and then upon occurrence of certain conditions, the entriescorresponding sequences from the first 32 kilobytes of the file areremoved, and entries corresponding to sequences from the next 32kilobytes of the file are added.

The conditions upon which the hash window are moved may be anyconditions which improve the execution time, performance, or compressionof the hashing algorithm. In one embodiment, the window is moved whenmatches have been found for more than 85% of the sequences in a givenhalf of the window. In another embodiment, the window is moved when agiven percentage of the second file has been compared with the existinghash entries. In one embodiment, the window is moved when hash valueshave been computed and compared for a proportionate portion of thesecond file compared to the first file. For example, if the first fileis 100 kilobytes, and the second file is 80 kilobytes, the hash windowmay be moved when 80/100*64 kilobytes of the second file has beencompared to sequences in the hash table.

After the network appliance 200 creates a hash table (step 711), thenetwork appliance 200 may then compute hash values for said secondplurality of sequences of data (step 713). Said hash values may becomputed according to the same method used to compute hash values forthe first plurality of sequences. The network appliance 200 may choosesequences of data from the second file in the same manner in which thenetwork appliance chose sequences of data from the first file. Forexample, if the network appliance 200 created hash table entriescorresponding to successive overlapping four-byte sequences from thefirst file, the network appliance may choose to compute hash values forsuccessive overlapping four-byte sequences from the second file.

After computing hash values for some or all of the second plurality ofsequences of data (step 713) the network appliance 200 may compare eachof the second plurality of sequences of data with sequences from thefirst plurality of sequences having the same hash value to determinesequences of data present in both files (step 715). The networkappliance may perform this step in accordance with any hashing algorithmpresently available. Said comparisons may comprise a comparison ofsubsequent bytes of matched sequences to determine longer matches. Forexample, the first file may comprise the sequence “abcdefghijklmno” andthe second file may comprise the sequence “zyxwvutcdefghituv.” If thehashing is done on successive four-byte sequences, the network appliance200 may determine that the sequence “cdef” is present in both files. Thenetwork appliance 200 may then compare subsequent bytes of the matchedsequences to determine that the sequence “cdefghi” is present in bothfiles. Thus in some embodiments the lengths of the sequences determinedto be present in both files may vary from the lengths of the sequencesfor which hash values are computed. In some embodiments a minimum andmaximum length on matching sequences may be set.

After determining sequences of data present in both files (step 715) thenetwork appliance 200 may store representations of lengths and locationsof said sequences of data present in both the first and second files(step 717). The network appliance 200 may store said representations inany storage medium, including a cache, RAM, a disk, or tape. In someembodiments, the network appliance 200 may store said representations onthe network appliance 200 itself. In other embodiments, the networkappliance 200 may store said representations on another computing device100. In some embodiments, lengths and locations of a sequences of datamay be stored while the network appliance 200 is comparing each of thesecond plurality of sequences of data with sequences from the firstplurality of sequences having the same hash value (step 713). In otherembodiments a minimum length may be required for the length and locationof a given sequence to be stored. In one embodiment, the minimum lengthmay be specified to be four bytes.

The representations of lengths and locations of said sequences presentin both files may comprise any representation which identifies a lengthand location of a sequence. In some embodiments the locations of saidsequences are stored as absolute locations within a file. In otherembodiments, the locations of said sequences are stored as locationsrelative to a given reference pointer within said first file. In oneembodiment, said reference pointer may be fixed, in another embodimentsaid reference pointer may move according to a rule set.

In one embodiment the reference pointer may be initially set to point tothe beginning of the first file. The pointer may then be incrementedevery time a matching sequence of longer than 5 bytes is found. Thepointer may then be incremented to point to the last byte plus one ofthe matching sequence in the first file. In this embodiment, locationsof said sequences present in both files are stored as a given numberbytes, positive or negative, from the position of the reference pointer.

In some embodiments, the lengths and locations of the matched sequencesare stored as fixed length integers. In one embodiment, the length of amatched sequence is stored as a 1 byte integer, wherein the integerrepresents a length of between 4 to 1027 bytes. In this embodiment,byte-lengths of matched sequences are restricted to multiples of 4. Inother embodiments, any other bit or byte length integers may be used tostore said sequence lengths. In still other embodiments, any otherrestrictions may be imposed on byte-lengths of matched sequences,including minimum and maximum lengths, and limiting byte lengths togiven multiples. In still other embodiments, lengths of matchedsequences may be stored as variable length integers. In some embodimentslocations of matched sequences may be stored as variable lengthintegers. In other embodiments, locations of matched sequences arestored as fixed length integers of a given byte or bit length.

After the network appliance 200 stores representations of lengths andlocations of said sequences of data present in both the first and secondfiles (step 717), the network appliance 200 may create a third filecomprising sequences of data from the second file and representations oflocations and lengths of said sequences of data present in both thefirst and second files. Said creation (step 717) may occur after all thelengths and locations of matched sequences are stored, or said creation(717) may occur contemporaneously as matched sequences are found. Thethird file may contain representations of lengths and locations in anyformat discussed herein. In some embodiments lengths and locations ofshared sequences may be preceded by special byte or bit sequences.

For example, if a first file comprised the string “abcdefghijklmnop,”and the second file comprised the string “xxxxxxxdefghijkxxxxxxcdefxxx”,the third file may comprise the sequence “xxxxxxx3,8xxxxxx2,4xxx”. Inthis example 3,8 is used to indicate a representation indicating thesequence from the first file starting at byte 3 and 8 bytes long (insome embodiments this representation could be two fixed-length binaryintegers). Likewise 2,4 indicates that a representation indicating thesequence from the first file starting at byte 2 and 4 bytes long.

As another example, if the first file comprised the string“abcdefghijklmnop,” and the second file comprised the string“xxxxxxxdefghijkxxxxxxcdefxxx”, the third file may comprise the sequence“xxxxxxx3,8xxxxxx-9,4xxx”. In this example, locations of sharedsequences are stored as relative distances from a reference pointer,incremented according to the method described above. In this example,the network appliance 200 indicates the first matched sequence in thesame manner as the previous example, since the reference pointerinitially points to the beginning of the first file. The referencepointer would then be incremented to point to location of the last byteplus one of the matching sequence in the first file. Thus, the secondmatched sequence is indicated with -9,4 which indicates that the secondmatched sequence occurs nine bytes prior to the byte following theprevious matched sequence in the first file.

In one embodiment, the third file may be encoded in a byte protocol,such as ASCII. In one embodiment, each group of 7 bytes of binary datamay be encoded as 8 bytes of ASCII characters. This conversion may bedone by any known conversion method. The ASCII characters may correspondto any existing character set definition, including ISO-8859-1. In someembodiments, the third file may comprise an HTML file. In oneembodiment, the third file may comprise a Javascript variable comprisingsaid sequences of data from the second file and representations oflocations and lengths of said sequences of data present in both thefirst and second files. In one embodiment, the third file may alsocomprise a Javascript function comprising functionality for assemblingsaid second file by processing said Javascript variable. In anotherembodiment the third file may contain a reference to a Javascriptfunction comprising said functionality.

The following HTML code illustrates one example of a third file that maybe transmitted to a client.

<HTML>  <HEAD>   <SCRIPT>     var updateFile = “~~~~~ “   <SCRIPT> </HEAD>  <BODY onload=createPage( updateFile )>  </BODY> </HTML>

In the above example, an HTML file comprises a Javascript variable named“updateFile.” Said variable may comprise sequences of data from thesecond file and representations of locations and lengths of saidsequences of data present in both the first and second files. Theexample above also comprises a call to a Javascript function named“createPage.” Said function, which may either be included with the HTMLfile or stored on the client, may comprise functionality for assemblingsaid second file using the data from the Javascript variable“updateFile.” In the example above, a standard HTML browser wouldexecute the “createPage” function upon loading the HTML page. The“createPage” function may also comprise functionality for altering theHTML page to display said second file once the second file is assembled.

After creating a third file comprising sequences of data from the secondfile and representations of locations and lengths of said sequences ofdata present in both the first and second files (step 719); and thenetwork appliance 200 may transmit the third file to a client (step721). Said transmission may occur via any of the networks and methodsdiscussed herein. The network appliance 200 may modify the third file inaccordance with any function performed by the network appliance 200including compression, acceleration and encryption.

In some embodiments, the network appliance 200 may transmit informationin the HTTP header of the transmission corresponding to the second file.To continue a previous example, the network appliance might insert thename-value pair “previously-stored-version=826482764” to indicate whichversion of the file was used as the first file for purposes of the filecomparison and compression.

After transmitting the third file to a client (step 721), the client 102may receive the third file (step 723); execute a Javascript function torecreate the second file comprising sequences of data from the secondfile and sequences in the first file indicated by the third file (step725); and display the second file (step 727). The client 102 may performthese steps in accordance with any of the embodiments described herein.

Referring now to FIG. 8, a flow diagram depicting another embodiment ofa method for creating efficient updates to a previously stored file isshown. In brief overview, the method comprises creating a hash tablewith entries corresponding to overlapping sequences of data in a firstfile (step 711); setting a reference pointer to the beginning of saidfirst file (step 801); computing a hash value for a sequence of data ina second file (step 713); and determining whether said sequence ispresent in both files (step 715). The method may then comprise eithermoving to the next sequence in the second file (step 809) or determininga total length for the matching sequence (step 803) and determiningwhether said length exceeds a minimum threshold (step 805). The methodmay then comprise either moving to the next sequence in the second file(step 809) or storing the length and location of the matching sequencerelative to reference pointer (step 717). The method may then comprisesetting the reference pointer to the last byte plus one of the matchingsequence in the first file (step 807) and then moving to the nextsequence in the second file (step 809). In the embodiment shown, themethod may be performed by a network appliance 200.

Still referring to FIG. 8, now in greater detail, a network appliance200 creates a hash table with entries corresponding to overlappingsequences of data in a first file (step 711). This step may be performedin accordance with any of the methods for creating a hash tabledescribed herein.

After creating a hash table with entries corresponding to overlappingsequences of data in a first file (step 711) the network appliance 200may set a reference pointer to the beginning of said first file (step801). The reference pointer may comprise any type of pointer.

After setting a reference pointer to the beginning of said first file(step 801), the network appliance 200 may compute a hash value for asequence of data in a second file (step 713). This step may be performedin accordance with any of the methods for computing a hash valuedescribed herein.

After computing a hash value for a sequence of data in a second file(step 713), the network appliance 200 may determine whether saidsequence is present in both files (step 715). This step may be performedin accordance with any of the methods described herein.

If a sequence is not present in both files, the network appliance 200may move to the next sequence of the second file (809). Said nextsequence may comprise any sequence occurring after the given sequence inthe second file. In one embodiment, the next sequence may be thesequence starting one byte after the previous sequence. In anotherembodiment, the next sequence may be the sequence starting any othernumber of bytes after the previous sequence. In some embodiments movingto the next sequence of the second file (step 809) may be accompanied bymoving a hash window as described previously herein. If no next sequenceexists, the method may terminate.

If a sequence is present in both files, the network appliance 200 maydetermine a total length of a matching sequence by comparing subsequentbytes of the matched sequences (step 803). The total length may bedetermined in accordance with any of the methods described herein.

The network appliance 200 may then determine if the total length of thematching sequence exceeds a given threshold (step 805). Thisdetermination may be made in accordance with any of the methodsdescribed herein. If the length of the matching sequence does not exceedthe minimum threshold, the network appliance 200 may move to the nextsequence of the second file.

If the length does exceed the minimum threshold, the network appliance200 may then store the length and location of the matching sequencerelative to the given reference pointer in accordance with any of themethods discussed herein. The network appliance 200 may then incrementthe reference pointer according to any of the methods described herein(step 807). The network appliance 200 may then move to the next sequenceof the second file (step 809).

Now referring to FIG. 9, one embodiment of a method for efficientlyreceiving updates to previously stored files is depicted. In briefoverview, said method comprises: receiving a assembly function (step903), receiving a first file comprising sequences of data (step 705);displaying said first file; storing said first file (step 708);receiving a third file comprising sequences of data and representationsof locations and lengths of sequences in the first file (step 723);executing a Javascript function to create a second file comprisingsequences of data from the second file and sequences in the first fileindicated by the third file (step 725); and displaying said second file(step 727).

Still referring to FIG. 9, now in greater detail, a network appliance200 may transmit a assembly function. Said assembly function maycomprise any computer readable program means for assembling a secondfile using a file comprising sequences of data from a second file andrepresentations of locations and lengths of said sequences of datapresent in both a first and second files. Said assembly function maycomprise any programming or scripting language, including Javascript, orJava. In some embodiments, the assembly function may be transmitted inaccordance with any of the other network appliance functions describedherein. In one embodiment, the assembly function may be included in aprogram providing other client-side acceleration functionality.

In the embodiment shown, after the network appliance 200 transmits aassembly function (step 901), a client 102 or client agent 120 receivesthe assembly function (step 903). The client may receive said assemblyfunction via any of the networks, protocols, or computing devicesdescribed herein. In some embodiments, the client 102 receives theassembly function from a network appliance 200. In one embodiment, theassembly function may be included as part of a client-side accelerationprogram. In other embodiments, the assembly function may be installed onthe client 102 via any means of transferring software, including via adisk or other portable storage device. In some embodiments, a clientagent 120 may receive and later execute the reassembly function suchthat the operation of the reassembly function is transparent to one ormore applications or network layers.

In the embodiment shown, after receiving a assembly function (step 903),the client 102 or client agent receives a first file comprisingsequences of data. In the embodiment shown, the client 102 receives thefirst file from a network appliance 200. In other embodiments, theclient 102 may receive the first file from any computing device. Saidfile may comprise any file type or protocol discussed herein.

After a client 102 receives a first file comprising sequences of data(step 705), the client 102 may display said first file (step 707). Thefile may be displayed in any manner appropriate for the given file. Insome embodiments, the file may be displayed in a web browser. In otherembodiments, the file may be displayed in a business application, suchas a word processor or a spreadsheet. In still other embodiments thefile may comprise a standalone application and be displayed as such. Insome embodiments, the file may correspond to an application running in avirtual computing environment. In one embodiment, the file maycorrespond to a remotely executing application. In another embodiment,the file may correspond to a streaming application.

After a client 102 displays said first file (step 707), the client 102or client agent 120 may store said first file (step 708). The client 102may store the first file in any storage element, including storing in acache, disk, flash memory, or RAM. In some embodiments, the client 102may compress the file for storage. In other embodiments the client 102may store only portions of the file. In some embodiments the client 102may store said first file (step 708) before or during the display ofsaid first file (step 707).

After a client 102 stores said first file (step 708), the client 102 orclient agent 120 may receive a third file (step 723). In the embodimentshown, the client 102 receives the third file from a network appliance200. In other embodiments, the client 102 may receive the third filefrom any computing device. Said file may comprise any file type orprotocol discussed herein. In some embodiments, the file may compriseASCII characters. In other embodiments, the file may comprise binarydata.

After a client 102 receives said third file (step 723), the client orclient agent 120 may execute a Javascript or other function to assemblea second file (step 725). In some embodiments, the Javascript functionmay be included in said third file. In other embodiments, the Javascriptfunction may be already stored on the client 102. In some embodiments,the Javascript function may be provided in a client-side accelerationprogram. In some embodiments, the third file may comprise a link to alocation where the client 102 may download the Javascript function.

The Javascript function may perform any technique, or the reverse of anytechnique described herein to assemble said second file. In someembodiments, the Javascript function may comprise the assembly functionreceived in step 903. In other embodiments, the Javascript function maycomprise a reference to said assembly function. In still otherembodiments, said Javascript function may comprise means for downloadingsaid assembly function.

After executing a Javascript function to assemble said second file (step725), the client may display said second file (step 727). The file maybe displayed in accordance with any of the methods described herein fordisplaying a file.

Referring now to FIG. 10, one embodiment of a method for assembling asecond file from a previously stored first file and a third filecomprising sequences of data from the second file and representations oflocations and lengths of sequences of data present in both a first andsecond files is shown. In brief overview, the method comprises reading aset of data from a third file (step 601) and determining whether saidset of data corresponds to a locations and length of said sequences ofdata present in both the first and second files (step 603). The methodthen may comprise reading the specified length of bytes at the specifiedlocation in said first file (step 605); adding said bytes to the secondfile (step 607); incrementing the reference pointer to the location ofthe last byte plus one of the bytes read from the first file (step 609);and moving to the next set of data from said third file (step 613). Inone embodiment, said method may be performed by a client 102 or clientagent 120. In another embodiment, said method may be performed by aassembly function as described in FIG. 9.

Still referring to FIG. 10, now in greater detail, a client 102 may seta reference pointer to the beginning of the first file. This may beperformed in accordance with any of the methods described herein.

After setting the reference pointer (step 601) a client 102 may read aset of data from a third file (step 602). Said set of data may compriseany number of bits or bytes of said third file. In one embodiment, saidset of data is then stored in a memory element or cache.

After reading said set of data (step 602), a client 102 may determinewhether said set of data corresponds to a length and location of asequence in the first file. In one embodiment, a client may determinewhether said set of data comprises a special character or bit sequence.

If said set of data does not correspond to a length and location of asequence in the first file, the client 102 may add said set of data tothe second file (step 611). Said addition may comprise appending saidset of data to the end of the second file. The client 102 may then moveto the next set of data from the third file (step 613).

If said data does correspond to a length and location of a sequence inthe first file, the client 102 may then read the specified length ofbytes at the specified location in the first file (step 605). The clientmay determine the length and location specified by recognizing any ofthe representations of lengths and locations described herein. In oneembodiment, the client may then store said specified bytes in a memoryelement or cache.

After reading the specified length of bytes at the specified location inthe first file (step 605), the client 102 may then add said bytes to thesecond file (step 607). Said addition may comprise appending said bytesto the end of the second file.

The client 102 may then increment the reference pointer to the locationof the last byte plus one of the bytes read from said first file (step609). This may be performed in accordance with any of the methodsdescribed herein. The client 102 may then move to the next set of datafrom said third file. (step 613).

Referring now to FIG. 11, one embodiment of a method for determining afile transmission method is shown. Said method may be performed by anyof the machines or combinations of machines described above, althoughthe embodiment below describes the method being performed by a networkappliance 200. In brief overview, the method comprises receiving arequest from a client 102 or client agent 120 for a resource (step1101); sending a request for said client's capabilities (step 1103);receiving information conveying said client's capabilities (step 1105);and determining a file transmission method (step (1107).

Still referring to FIG. 11, now in greater detail, the network appliance200 receives a request from a client or client agent 120 (step 1101). Inone embodiment receiving a request from a client (step 1101) comprisesreceiving a request directly from a client. In other embodiments, therequest from a client 102 may be received from any of the networks,connections, and appliances previously discussed. Said request maycomprise any of the protocols previously discussed. In some embodimentsthe request may comprise the request exactly as transmitted from theclient 102. In other embodiments the request may comprise a modificationof an original request from a client 102. Said modifications maycomprise modifications in the course of providing any of the networkappliance services discussed above, and any other modifications to thecontent, format, protocol, addressing, headers, or other portions of therequest. request from a client 102, or a new request. A request maycomprise a resource directly requested by a client 102, and it maycomprise a resource requested in the course of performing any servicefor the client 102.

After receiving a request from a client (step 1101), the networkappliance 200 sends a request for said client's capabilities (step1103). In one embodiment, said request may be sent to the client 102. Inanother embodiment, request may be sent to a collection agent asdescribed in U.S. patent application Ser. No. 10/956,832 “A METHOD ANDAPPARATUS FOR ASSIGNING ACCESS CONTROL LEVELS IN PROVIDING ACCESS TONETWORKED CONTENT FILES” whose contents are expressly incorporatedherein by reference. Said collection agent may reside on the samephysical machine as the network appliance sending the request, or theymay reside on different physical machines. Said request may also be sentto a file, a cache, a database, a server, an executing application, orany other source of information concerning the client 102.

After sending a request for the client's capabilities (step 1103) thenetwork appliance 200 receives information conveying said clientscapabilities (step 1105). Said information may be received from a client102, or client agent 120, a collection agent, a file, a cache, adatabase, a server, an executing application, or any other source ofinformation concerning the client 102. Said information may comprise,without limitation machine ID of a client node 102, operating systemtype, existence of a patch to an operating system, MAC addresses ofinstalled network cards, a digital watermark on the client device,membership in an Active Directory, existence of a virus scanner,existence of a personal firewall, an HTTP header, browser type, devicetype, network connection information, authorization credentials, and anyof the other capabilities or preferences discussed above. In someembodiments, the network appliance may store or cache said informationfor later retrieval.

After receiving information conveying said clients capabilities (step1105); the network appliance may determine a file transmission methodcorresponding to said client 102 or client agent 120 (step 1107). Saiddetermination may be made on the basis of any of the informationreceived.

In some embodiments, the network appliance 200 may determine, inresponse to information received in step 1105, to transmit files inaccordance with the method for creating efficient updates to apreviously stored file described in FIG. 7. In one embodiment, saiddetermination may be made in response to information corresponding tothe client's 102 memory size, connection speed, connection bandwidth,processor speed, or the prior existence of a stored file.

In some embodiments, the network appliance 200 may determine, inresponse to information received in step 1105, to transmit a assemblyfunction to the client 102. For example, the network appliance maytransmit a assembly function to a client 102 if the network appliance200 receives information that the client 102 does not possess theassembly function, and the information indicates the client has thecapability to execute a assembly function. In some embodiments, saidassembly function may be transmitted along with any other files,including requested content files, or other files transmitted inaccordance with the functions of the network appliance 200. In someembodiments, a network appliance may possess a plurality of assemblyfunctions. For example, a network appliance 200 may possess a number ofassembly functions optimized for different computing environments,operating systems, and hardware configurations. The network appliancemay then determine, in response to the information received in step1105, which assembly function to transmit to a client 102.

While the invention has been particularly shown and described withreference to specific preferred embodiments, it should be understood bythose skilled in the art that various changes in form and detail may bemade therein departing from the spirit and scope of the invention asdefined by the appended claims.

1. A method for using a client agent to enable http cookieauthentication in non-HTTP communications from a client, the methodcomprising: (a) intercepting, by a client agent executing on a client, aconnection request from the client; (b) establishing, by the clientagent, a transport layer virtual private network connection with anetwork appliance; (c) transmitting, by the client agent via theestablished connection, an HTTP request comprising an authenticationcookie; and (d) transmitting, by the client agent via the connection,the connection request.
 2. The method of claim 1, wherein the clientagent executes transparently with respect to one of the followingnetwork layers: the application layer, the presentation layer, thesession layer, or the transport layer.
 3. The method of claim 1, whereinstep (a) comprises intercepting, by a client agent executing on aclient, a transport layer connection request from the client, whereinthe interception occurs at one of the following network layers: thetransport layer, the network layer, or the data layer.
 4. The method ofclaim 1, wherein step (a) comprises intercepting, by a client agentexecuting on a client, a TCP SYN packet.
 5. The method of claim 1,wherein step (c) comprises transmitting, by the client agent via theestablished connection, an HTTP request comprising an authenticationcookie prior to any data being transmitted via the connection.
 6. Themethod of claim 1, wherein step (c) comprises transmitting by the clientagent, in response to the determination that the connection has beenestablished, an HTTP request comprising an authentication cookie, thecookie comprising user authentication credentials.
 7. The method ofclaim 1, wherein step (c) comprises transmitting, by the client agentvia the established connection, an HTTP request comprising anauthentication cookie, the cookie comprising application-specificauthentication credentials.
 8. The method of claim 1, wherein step (c)further comprises receiving, by the client agent, an HTTP response, theHTTP response comprising an acceptance of the authentication cookie. 9.A computer implemented system for using a client agent to enable HTTPcookie authentication in non-HTTP communications from a client, thesystem comprising: a client computing device; and a client agentexecuting on the client, which intercepts a connection request from theclient; establishes a transport layer virtual private network connectionwith a network appliance; transmits, by the client agent via theestablished connection, an HTTP request comprising an authenticationcookie; and transmits, by the client agent via the connection, theconnection request.
 10. The system of claim 0, wherein the client agentexecutes transparently with respect to one of the following networklayers: the application layer, the presentation layer, the sessionlayer, or the transport layer.
 11. The system of claim 0, wherein theclient agent intercepts a transport-layer connection request from theclient, wherein the interception occurs at one of the following networklayers: the transport layer, the network layer, or the data layer. 12.The system of claim 0, wherein the client agent intercepts a TCP SYNpacket.
 13. The system of claim 0, wherein the client agent transmits,via the established connection, an HTTP request comprising anauthentication cookie prior to any data being transmitted via theconnection.
 14. The system of claim 0, wherein the client agenttransmits, via the established connection, an HTTP request comprising anauthentication cookie, the cookie comprising user authenticationcredentials.
 15. The system of claim 0, wherein the client agenttransmits, via the established connection, an HTTP request comprising anauthentication cookie, the cookie comprising application-specificauthentication credentials.
 16. The system of claim 0, wherein theclient agent receives an HTTP response, the HTTP response comprising anacceptance of the authentication cookie.